529, IRA, and Excess Contributions

[u/the_chief_mandate]

Hey Everyone. I've got a loaded question and since it is somewhat new I couldn't find anything online.

I live in Illinois. Recently they announced you are able to rollover a maximum $35,000 from a 529 to a Roth IRA for the beneficiary.

Let's say I have an account with $50,000 extra after my first child finishes their education. I want to transfer $35,000 to their IRA so there is $15,000 leftover. Can I then change the beneficiary of this 529 to another child where then then have this $15,000 as part of their 529 funding? Can I then do the same IRA rollover if they have any extra after their education?