Tianna Rooney has already bought the poster board for the sign she'll wave when the 16-year-old refugee boy her family is taking in arrives in the United States.

Rooney, a 39-year-old family therapist and mother of two from suburban Detroit, knows the exact words of welcome she'll write on it, in the teenager's native language from the African country of Eritrea.

But Rooney's family is leaving the sign blank, for now. She and her husband, Todd, fear actually writing the words 'Welcome Home' could break her heart.

The foster son they're waiting for is part of a small, three-decade-old US program for so-called unaccompanied refugee minors that has been halted by a series of new refugee bans and travel limits imposed by the Trump administration in the name of fighting terrorism.

Tianna Rooney, a 39-year-old family therapist and mother of two from suburban Detroit, is hoping to foster a 16-year-old male who is fleeing violence in the African country of Eritrea

One of the last refugee foster children to enter the US before the ban, a 16-year-old from Eritrea, is seen hugging sponsor Julie Rajagopal in San Francisco's Dolores Park

By blocking the program, the US travel bans have stranded more than 100 refugee children who were already matched to waiting American foster families.

Without parents or other adult relatives, those kids are living on their own in countries of temporary refuge, in limbo while their US foster parents hope for a court ruling that will allow the children to finish their journeys.

Since the June day a refugee agency matched the Rooneys with their foster son, which turned out to be the same day of the first Supreme Court ruling barring him, 'we have experienced this very unexpected ride of grief in our family,' says Rooney.

Meanwhile, the boy who fled his home country at 13 to avoid widespread forced military conscription of children continues to fend for himself on the streets in his temporary refuge in another African capital, with no phone or internet for the Rooneys to reach him to explain the delay.

'There's part of me that really hopes he knows a family wants him,' Tianna Rooney says.

Since the 1980s, the program for unaccompanied refugee children has brought in more than 6,000 refugee children, including 203 last year.

'These are kids on their own, and struggling to survive,' said Elizabeth Foydel, policy counsel with the International Refugee Assistance Project, a Washington, DC, legal-aid group for refugees.

'How long do you feel comfortable with your child not having a caregiver?' Foydel says she asks other Americans. 'Trying to manage for themselves?'

Sharon Martin is waiting to host a 17-year-old couple from Myanmar and the baby they had together, under an unaccompanied refugee minor program that has now been halted

Martin, 64, has bought a crib for the young refugee family from Myanmar and says she looks forward to reading to their child, something she misses

The program for unaccompanied refugee children from around the world is different from one started by the Obama administration in 2014 for Central American children fleeing a surge in violence there.

In the program for unaccompanied refugee children, kids eking out a living by themselves in a refugee camp or elsewhere must first come to the attention of a UN agency, which may choose to refer them for the US foster program, especially if the children are deemed to be particularly vulnerable wherever they are now.

The children must then pass US security screenings and other requirements, and win a match with an American foster family or group home.

But a series of Trump administration orders, and court rulings interpreting them, are now barring refugees with no close family in the United States.

That requirement shuts out the refugee children in the foster program, who have no relatives they can turn to in the US.

The child refugees newly blocked from waiting American foster families include five Ethiopian sisters, ages 9 to 16.

The girls lost both parents in 2009, and have faced abuse alone in the war zone of neighboring South Sudan and in Sudanese cities, said Jessica Jones, policy counsel for the Baltimore-based Lutheran Immigration and Refugee Service.

Along with the US Conference of Catholic Bishops, the Lutherans are one of two U.S. groups running the program on behalf of the US State Department.

Other waiting children include a 17-year-old couple and the baby they had together in a refugee camp, where they were fleeing attacks on their Rohingya religious minority in Myanmar.

In her home in a Detroit suburb, Sharon Martin, 64, has bought a crib for the young refugee family from Myanmar.

But the children's books she bought, Martin said, are really for her. 'If they come, I can finally read to a child again,' Martin says.

Refugee workers say the family faces forced return to Myanmar if their US arrangements fall through.

In San Francisco, meanwhile, web designer Julie Rajagopal and husband Mike Gougherty, a senior planner for a regional ferry system, are two of the lucky ones.

The 16-year-old boy they are fostering also fled a lifetime of forced military service in Eritrea, at 13.

When he landed in March, a slight youth coming off the plane in an ill-made tracksuit, he was among the last refugee foster children to make it into the US.

Web designer Julie Rajagopal and husband Mike Gougherty, a senior planner for a regional ferry system, were among the last to welcome a refugee foster child before the ban

Rajagopal, 35, often had stayed up through the night calling government workers and charity officials in the faraway African hub of Cairo to speed her new foster son's paperwork.

On a clear day this summer, the teen strolled with the couple at a park overlooking San Francisco.

In the city's hip Mission District, he wore a red sweater and shoes he carefully matched himself, and jeans he insisted on lovingly ironing with each wear.

Meanwhile, in Brighton, the Rooneys and their 10- and 12-year-old sons stack new socks and T-shirts in the bedroom they've set aside for the boy they nicknamed 'Five,' meaning the eagerly awaited fifth member of their family.

Tianna Rooney recently got out the poster board, thinking to work on the welcome sign. After a concerned look from her husband, she put it away.

'We want to think positive thoughts' that their foster son will come safely, Todd Rooney said. 'But without endangering ourselves. Without setting ourselves up for a heartache.'