Ben Affleck and Jennifer Lopez's Kids Were 'All Dancing' Together at Couple's Star-Studded Christmas Party

Ben Affleck and Jennifer Lopez are feeling festive!

According to an insider, on Saturday, December 16, the couple threw a star-studded shindig at their home in Los Angeles.

An insider said the bash was "really fun," noting, "they were both in such good spirits," with the mom-of-two, 54, showing off her vocal chops by singing a few Christmas tunes.

Famous guests included Margot Robbie, Michael B. Jordan and the Oscar winner's brother.

"The kids were all there dancing and having a great time, especially the twins and Violet [Affleck]," the source added of their blended brood, referring to Max and Emme Muñiz, 15, whom Lopez shares with ex-husband Marc Anthony.

Affleck shares Violet, 18, Seraphina, 14, and Samuel, 11 with ex-wife Jennifer Garner.

In a past interview, Lopez detailed how she and her husband blended their families.

"Everything is really good right now and should be the same in the near and distant future," she spilled. "The transition is a process that needs to be handled with so much care. They have so many feelings. They’re teens. But it’s going really well so far."

"What I hope to cultivate with our family is that his kids have a new ally in me and my kids have a new ally in him, someone who really loves and cares about them but can have a different perspective and help me see things that I can’t see with my kids because I’m so emotionally tied up," added the triple threat.

While the party was smooth sailing, a separate source claimed the actual holiday could be a little more stressful since the duo's parents allegedly don't have the best relationship.

"They both want their moms to fly in and spend time together, but Christine [Affleck] has never really gelled with Lupe [Lopez], so they've always been tactfully kept apart," the source claimed of the matriarchs. Per the source, the Good Will Hunting star's mother has been "wary" of his second marriage.

"Jennifer and Ben have this [vision] of the perfect Christmas, with in-laws toasting and hugging. But the reality is far from it," the insider said.

It's unclear who the kids will spend the holidays with, but as OK! reported, the Argo star and his former spouse, both 51, have a "mature" co-parenting relationship.

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Even better, the dad-of-three approves of the Alias alum's boyfriend John Miller.

"Ben is super down-to-earth, and so is John," the insider claimed. "They have a mutual respect for each other and are always very friendly with one another."

People reported on the party.