Jennifer Lopez and Ben Affleck are "in it for the long run".
The 52-year-old star and Ben, 49, rekindled their romance earlier this year, and they recently brought their families together for a trip to The Magic Castle in Los Angeles, as their relationship moves to the next stage.
A source explained: "Since Jennifer and Ben are in it for the long run, it's just a natural step that they all spend time together with the kids."
Jennifer - who has 13-year-old twins Emme and Maximilian with her ex-husband Marc Anthony - is determined not to rush anything.
But at the same time, she recognises the need to introduce them to Ben, who has Samuel, nine, Seraphina, 12, and Violet, 15, with his ex-wife Jennifer Garner.
The insider explained to People: "They are not trying to rush anything, but they want all the kids to get to know each other.
"They are making the last few days of summer as fun as they can. Soon it's back to school and work."
Meanwhile, Ben recently spent time bonding with Jennifer's mother.
The Hollywood star and Guadalupe developed a good relationship when the celebrity duo first dated in the early 2000s, and she is "thrilled that they are back together now".
A source said: "In the past, Jennifer's mom and Ben were very close. Guadalupe loved Ben. She was sad when they couldn't work things out years ago.
"She is thrilled that they are back together now."
Ben and Guadalupe spent time together in Las Vegas, and Jennifer is delighted that they're getting along so well.
The insider added: "Jennifer is very close with her mom. It's very important to her that the person she is with, gets along with her mom.
"Jennifer loves that Ben and Guadalupe hung out in Las Vegas. They both love gambling and had fun together at the Wynn hotel."