Four upstate sisters out celebrating the youngest one’s birthday with...

The four sisters killed in the upstate limo crash will be united in death.

A group funeral will be held for Amy King Steenburg, 29, Allison King, 32, Mary King Dyson, 33, and Abigail King Jackson, 34 — as well as Mary and Abigail’s husbands — on Saturday, the sisters’ grieving brother told The Post in an exclusive interview Tuesday.

“The girls are being buried together, although I don’t think I can say buried because all my sisters are being cremated,” sibling Tom King said outside his parents’ home in rural Amsterdam, about 35 miles northwest of Albany.

Tentative plans call for a massive wake at the Betz, Rossi, Bellinger & Stewart Funeral Home in Amsterdam on Friday, followed by the funeral services Saturday at St. Stanislaus Roman Catholic Church in Amsterdam, he said.

“It depends on the release of their bodies,” said King, 36. “As of last night, [authorities had] only ID’d 10 bodies,’’ or half of those killed in the horror.

King, one of seven siblings, said authorities “asked us for dental records, and tattoo and jewelry identification.”

“It’s been real hard,” he said.

“As of this morning, I believe my sisters have been identified.”

Amy Steenburg would have turned 30 on Wednesday. The group was killed when their limo crashed in upstate Schoharie on Saturday afternoon during a birthday celebration for her.

Steenberg’s newlywed husband, Axel Steenburg, was also among the total 20 dead, as was his brother Rich.

King said a separate funeral will be held for the brothers.

Rich’s girlfriend was scheduled to join in the fateful trip to the Ommegang brewery in Cooperstown but stayed home because she was sick, King said.

“That’s the only reason she’s alive,” he said.

The three children left orphaned by the tragedy — ranging in age from 16 months to 4 years — will be raised by their godparents, King said.

“My sisters who had kids, they both had wills, so everything is laid out about who gets their kids and their wishes will be honored,” he said.

King said the tragedy has been especially difficult for his parents, who are “torn up inside and haven’t let that go yet.

“My brother and I, we are trying to keep their daily routine as normal as possible, but we can’t. There’s nothing normal about this,” he said.

“They’re trying to — they’re not falling apart, but with the kids and the property, its weighing on them heavily. They’re trying to decide how to take care of all the houses and cars and stuff.”

King said he finally “broke the news to my son yesterday, and he got real upset.” His son is 6.

“I got upset telling him and I guess he fed off my energy, and the both of us were — it was tough,” King said.

At one point, the enormity of his family’s loss appeared to overwhelm King, who gazed upward and pressed his lips together after describing how close they’d all been.

“We had a fantasy football league in the family. There was 10 of us in the pool,” he said.

“Now, there’s four of us left. Six of us died in that accident.”