Tricky One - Buying out a GF through an LLC

First-time poster. Me and my GF split after purchasing a house together 50/50. I am buying her out for her downpayment + any principal payments, call it 75k, and then turning it into a rental property. I've formed an LLC with us both as managing members and we have agreed to a buyout clause for her interest in the company for the 75k payment.

Now apparently, My loan servicer said I can transfer both the title AND the liability to the LLC. This LLC has formed 7 days ago and has no credit so I will have to personally guarantee the loan. However, I'm not sure if I will be enough...why would the bank give up one of the people they can hold liable? Seems like a bad move on their part.

So onto my question. Can I add a parent to my LLC as a member (Me with 51%, Parent with 44%, Ex Gf with 5%) to help secure the loan transfer? Would a lender/servicer look at my LLC operating agreement and allow the 2 members with the largest % ownership to guarantee the loan even though my Ex was on the original loan?

The goal here is to get her name off of the title and the mortgage upon payout. 

Appreciate any feedback!