This unit has already been indicated by the city that it can be approved as a 3rd unit.

Less than an hours work, everything online approved within a few days.I recently decided to stretch myself a bit and start putting my holdings into series LLCs. 

Well anyone can write anything into a contract, but whether it is legal and enforceable is for the courts to decide...It is State law here that a contractor must call 811 or they are liable for the costs.

It's usually the member/borrower's creditworthiness that is the issue and interferes with approval, not the LLC. 

The purchase contract makes the buyer legally responsible for the loan. 

Start by getting pre-approved for a loan, ensuring your credit score, debt-to-income ratio, and finances meet lender requirements.

Is it legal to offer to rent the property back to the homeowner who already lost their home to foreclosure when negotiating the redemption rights purchase? 

I am focusing on the part of your post asking -"would it be legal".

How does that work when you are not yet the legal owner of the property?

Quote from @Jaikevis Reams: In order to put a property under contract I need to provide proof of funds I know that I can get that from a hard money lender but I don’t meet there criteria for a loan approval what should I do?