Your numbers look pretty good to me. The obvious problem is that you likely can't predict the amount of support your kids will need and how much that will cost so hard to model. My daughter is 20 and I still don't have a good idea as she is still at home. You probably know but you can move 529 funds in to an ABLE account but amounts over 100k will make them ineligible for government programs for which they are otherwise eligible so would probably be wise to get some money moved over and start using those funds to help support your kids now.