The 11-year-old love child of late investment banker and New York magazine owner Bruce Wasserstein claims her five half siblings are trying to cheat her on the value of his Hamptons mansion as they divvy up his $2.3 billion estate.

In addition to six kids, Wasserstein, who died in 2009 at age 61, left behind a widow, two ex-wives, a mistress, and four lavish residences: a London townhouse, a Paris apartment, a 17-acre Santa Barbara estate, and a sprawling 27.5-acre oceanfront East Hampton property known as Cranberry Dune.

Mistress Erin McCarthy, who gave birth to the youngest child, Sky, in 2008 while Wasserstein was still married to his third wife, Claude, claims his other kids agreed to give Sky her share of the value of his properties in cash if she and the girl agreed never to visit the homes.

The trustees overseeing the estate sold three of the four homes before reaching the 2015 deal with McCarthy, but Sky hasn’t gotten a penny from the property deal since the two sides are still squabbling over how much Cranberry Dune is worth.

The estate insists the Further Lane property, which includes a 23,500-square-foot, seven-bedroom manse, is worth just $120 million.

McCarthy, who called Cranberry Dune “one of the finest personal residences in the Hamptons,” places the price tag closer to $160 million, according to Manhattan Surrogate Court papers she filed in May that ask a judge to resolve the dispute.

Cranberry Dune consists of five lots next to Jerry Seinfeld’s home, and boasts a tennis court, a pool, and five fireplaces.

Sky, now 11, is already sitting on a $75 million inheritance, in addition to any money she would get from giving up the right to use her dad’s properties. She lives with her mom in a Central Park West pad.

Since Wasserstein’s death, his estate has paid “tens of thousands” in monthly child support to Sky and shelled out nearly $200,000 for her to rent a luxury Hamptons home each summer.

Wasserstein’s five older children from his two ex-wives have never sought out a “sincere or meaningful personal relationship” with the girl, her mom charges.

The Wasserstein kids — adults Pamela, Ben and Scoop, and teenagers Jack and Dash — blame McCarthy for splitting up their family and accuse her of breaking into Cranberry Dune in the middle of the night when Sky was an infant, screaming “You’re dad’s a bastard” at his youngest sons, who were then not even 10. McCarthy denied breaking in.

Pam Wasserstein insisted in a 2012 court affidavit that sharing Cranberry Dune with McCarthy and Sky “would be a source of unimaginable stress and trauma for my brothers and me.”

“We would rather sell these homes than live under those circumstances. That would be a shame, since we have lost so much already as a result of [McCarthy’s] relationship with our father — our father’s time and attention before his death, our family togetherness, and our sense of safety following [McCarthy’s] break-in.”

But McCarthy insists Sky’s getting swindled as the trustees overseeing Wasserstein’s estate are “unable or unwilling to determine the fair market value of Cranberry Dune … [and] unwilling to treat Sky fairly.”