Manchester City’s purchase of the La Liga club Girona last week combined a billionaire’s swagger with an uneasy impression of keeping business in the family. The unprecedented deal presents a dizzying clutch of questions, the most glaring one concerning the partnership with the agent Pere Guardiola in the joint 88% acquisition of another club. Of all the football deals in all the world, what attracted Manchester City’s Abu Dhabi owner and executives to go into business with their manager Pep Guardiola’s brother and agent?

Inquiries of the Football Association, which has detailed regulations seeking to prevent agents, managers and clubs working incestuously together and having conflicts of interest, produces the answer that no rules have been broken. Pere Guardiola, agent to Luis Suárez, Andrés Iniesta and many other mostly Spanish players including two at City, is a registered intermediary (the new term for agent) with the English and Spanish FA.

The FA does have a regulation, E4, headed “restriction on conflict of interest”, which prohibits a club, club official or manager from having “any interest in the business or affairs of an intermediary”. City and Pere Guardiola are confident that Pep, who will be sending players to Girona on loan, to his brother and agent’s benefit, is not caught in a conflict of interest.

Rule E4 also states boldly that “an intermediary shall not have an interest in a Club”, which seems to catch Pere Guardiola. The purpose is to guard against the very obvious risk that an agent could move players in and out and take fees to suit his own opportunities to make money, rather than make recruitment decisions solely in the best interests of the club.

However, the FA says that the rule restricts agents from having an interest or influence only in an English club. This prohibition on a conflict of interest does not apply to buying into an overseas club. City are understood to have been given this assurance by the FA before they moved from their informal partnership with Pere Guardiola and Girona, in which several City players have been loaned to the Spanish club over the past two years, to a formal deal. The Spanish FA does not have a similar restriction, so Pere Guardiola was free to buy his 44.3% share of the Catalan club, with The City Football Group – the overarching global corporation owned by Sheikh Mansour bin Zayed al-Nayan – buying an equal 44.3% stake.

City’s Catalan and former Barcelona chief executive, Ferran Soriano, and director of football, Txiki Begiristain, who know and worked closely with the Guardiola brothers during Barça’s glory years and lobbied ceaselessly to attract Pep to City, have been central to concluding this deal to buy Girona with Pere.

Pere Guardiola, the manager’s brother, has taken a 44.3% share in Girona. Photograph: Miguel Angel Molina/Marca/Offside

The attractions for their Abu Dhabi employer are said to be that more of the players increasingly accumulated at City from young ages can be loaned for polishing in La Liga, and that buying the club is an investment. The whole 88.6% of Girona, a small club in a charming ground promoted to La Liga for the first time in its history last season, is said to have cost €7m (£6.5m), which looks like remarkable value. If City’s aim is to make money from their stake increasing in value, then they are also helping Pere do the same.

So another club has been added to the Abu Dhabi portfolio centred on east Manchester, but Girona is much closer to home than the others of Mansour’s empire. His executives, surveying the football business after he bought City in 2008, decided early on to attain economies of scale and a global reach for sponsors by buying clubs on other continents.

The New York City MLS franchise buys a stake at the centre of soccer’s growth in the US; Melbourne Heart, the name changed to City and kit changed to blue, was aimed at securing a presence not only in Australia but Pacific Asia too; the most recent move was to obtain a foothold in South America with the purchase of Club Atlético Torque in Uruguay. The minority stake in Japan’s Yokohama F Marinos was driven by City’s Japanese global sponsor, Nissan. Having sold 13% of the City Football Group to China Media Capital for £265m in December 2015, City’s executives are now looking to invest in a club in China.

City have been lending Girona players since Pere Guardiola became involved there, when the shares were bought by the French media company TVSE Futbol, in the summer of 2015, before City finally secured Pep’s signature as City’s manager. The principal purpose of buying the club is said to be the football one: maintaining a finishing school to which City can send players whom Pep is not selecting in the Premier League.

Mansour’s executives have famously invested hugely in youth development since his takeover, opening their vast, cutting-edge, £200m campus next to the Etihad Stadium in December 2014. Yet for all that spending, global scouting and buying of young overseas players, the chances for most to play in the first team remain vanishingly small.

Into Mansour’s 10th year of ownership, including eye-watering expenditure in this summer’s transfer window, City have paid approximately £1.2bn to buy players, mostly top class, ready-made and in their prime, to win the Premier League twice and become Champions League regulars. The only player from the academy to approach playing for the first team regularly was Kelechi Iheanacho. Now 20, he was hardly a Manchester boy made good; he was coveted by many top clubs after starring for Nigeria in the 2013 under-17 World Cup, and City signed him in 2014 aged 17. Having made 12 full league appearances in three seasons, and 34 as substitute, Iheanacho has been sold this summer to Leicester City for £25m.

The academy graduates Mansour inherited have departed, notably Stephen Ireland and Micah Richards, and Pep Guardiola’s first major act, a statement of intent last year, was to cast out Joe Hart, whom City fans had watched mature from a 19-year-old signing from Shrewsbury to the captain and England goalkeeper.

City – like all Premier League clubs but more so given the scale of their investment in the campus – are increasingly recognising that they have a serious problem giving opportunities to the flocks of young players they strain to attract. The Girona deal is being presented as a way of easing that logjam; five City players are there on loan. City also have a lending partnership with the Eredivisie club NAC Breda – no fewer than six City players featured in their game against PSV Eindhoven last weekend, a 4-1 defeat. City’s senior football administrator, Brian Marwood, and Soriano and Begiristain, have fostered a web of other arrangements and partnerships with clubs in England and overseas to support their own youth development system.

Raheem Sterling chases the ball with Alcalá in hot pursuit during Manchester City’s pre-season friendly against Girona. Photograph: Pedro Salado/Action Plus via Getty Images

“The buying of Girona is a logical consequence of City’s group strategy and the concentration of wealth in European football,” says Raffaele Poli, head of the CIES Football Observatory, which analyses statistics and trends. “As with other partner clubs, Girona will allow City to develop players and make more of a profit out of them if they sell them – only a few will ever play for Manchester City.”

CIES performance analysis has sought to quantify the increase in market value City are achieving by sending to Girona their players: Pablo Maffeo, 20, the Spanish right-back signed from Barcelona in 2013; Aleix García, the 20-year-old attacking midfielder signed from Villarreal; Marlos Moreno, also 20, a Colombian striker, and the 24-year-old Nigerian striker Larry Kayode. The fifth City player there is Douglas Luiz, the 19-year-old midfielder signed this summer from the Brazilian club Vasco da Gama, and immediately loaned out.

This is the first time City have bought into a European club, and it raises fraught questions about independence and integrity, as well as the Premier League clubs’ stockpiling of young players. Despite the jarring feel to football’s sporting traditions, there are no rules against “dual ownership” in itself, but if two such clubs play each other, the authorities recognise a risk to genuine competition. City anticipated this potential problem should Girona ever succeed in qualifying for the Champions League and believe they could mount an argument that their arrangement is not caught by Uefa’s restrictions.

Uefa’s rules state that “No individual or legal entity may have control or influence over more than one club participating in a Uefa club competition”.

One definition of “control”, owning a majority of both clubs, will not apply because City have structured the deal at 44% apiece with their manager’s brother. The one which could catch the relationship with Girona defines control as “being able to exercise by any means a decisive influence in the decision-making” of both clubs. City accept this is a possible description of how the relationship will work – they will surely want some decisive influence – but they are prepared to argue.

The recent decision by Uefa’s “adjudicatory chamber” to allow Red Bull Salzburg and RB Leipzig to play in the Champions League – it decided that Red Bull is only a sponsor and does not own Salzburg and does not operate a “decisive influence” on both clubs – has given City’s lawyers encouragement.

During the phenomenal nine-year transformation of City from hapless local club to Abu Dhabi-owned global corporation, Mansour’s executives have prided themselves, for all the £1.2bn spent, on avoiding the less savoury, incestuous areas of the business. They have embraced City’s founding church roots and developed a fondness for a motto associated with William and Charles Clegg, the austere, Methodist directors of Sheffield Wednesday, a century ago – “Nobody gets lost on a straight road”.

With this purchase of Girona the City hierarchy is giving the impression of straining to please Pep Guardiola, and the road they are taking looks to have become just a little narrow, and winding.