C.S.
I have a "two finger" seperation in my abs and my kids are 6 and 4. Once they seperate so far, they don't go back together without surgery...
That being said, there are lots of exercises that you can do to minimize the issue. Try search Workouts to correct diastasis recti (or seperated Abs). Its all about building Core strength. Doing traditional crunches can actually make the issue worse!