Kittens at 7 weeks want to play.Advice needed

Saffron and Sachi want to play with the big cats. They are starting to get restless in their room. The problem is that they are still so tiny and my house has way too many nooks and crannies for them to hide or get stuck in and they are very fast.
When should they be allowed to mingle. When I brought the boys home they were 3 months old and came out to play two weeks after that.
What is the best thing to do for their own safety. The big cats like them and accept them.

Are you planning on giving at least 1st shots? If so, wait till they get the first shots. Then do some supervised interaction between the kittens and adults. Do NOT leave the house without finding where every kitten is Its easier to let them play for 15-30 mins and then put them back. Do this a few times a day if possible. Block off as much little hiding places as you can for awhile.