@Brian Gonsalves in short talk to a CPA about how it will effect your taxes, and a lawyer on how to handle the transition and setup from your parents to an llc that you and your sister would be running along with how that is going to effect child support (this might be more than one lawyer family lawyers sometimes don't do business law).
Side note borrowing on properties that are under a llc can be more difficult than an individual that is looking to borrow against. So I would add a banker/lender to the mix and make sure that if you do all of this you will still be able to obtain the financing you are looking for.
Hope that helps and congrats on the rapid expansion
Sounds like you are creating LOTS of tax issues. Call a CPA and also, maybe pump the breaks on changing ownership and llc's. Why not see if you are capable and willing to manage your parents portfolio before you make it your business? LLC's and ownership changes and all that can come in time.
"This has been working for years, change everything" is making me nervous for you.
I have a great CPA in the area if you PM me I'd be happy to refer you.
That does. Thank you for your help