Looks like Mady and Cara Gosselin's 9th birthday didn't turn into WWIII after all.
Jon, 32, celebrated his twin daughters' birthday with estranged wife Kate, 34, inside their $1.1 million home Thursday.
"We kept it cordial for the kids," he told Usmagazine.com outside.
The dad of eight picked up the kids from the bus stop after school earlier in the day, and said he planned to stay "awhile" but not overnight.
"I'm gonna stay and put my kids to bed," he said.
When asked about his interactions with Kate, Jon rolled his eyes -- but said things were going "fine."
Earlier Thursday, Jon scoffed that he was preparing for war with Kate because she was trying to change their joint-custody arrangement so that he could only be present at their home from 4 to 6 p.m.
"I won't allow that," he told Entertainment Tonight. "She's basically saying it would be too stressful to the kids to have both of us here, like we originally planned.
"I'm just going to stay," Jon -- who showed up toting a cake with his daughter's name misspelled as "Maddy" -- previously remarked. "I own the house, so I can do what I want."
Continued Jon: "She's trying to prevent me from seeing my kids on their birthday because she doesn't want to see me. She doesn't want to hear my apology. She doesn't want to work things out."