I am not an attorney. I am answering the post for entertainment purposes only and this is not constructed to legal advise. Make sure you talk to attorney about ANY legalities with this strategy.
Let's just think of this as a case study and theory only.
Before I answer this... I personally use sub-2s for "short term financing" (To fix up and flip) OR if the sellers know 100% that I have to rent the property out for a long period of time before I sell it and they are cool with it and I want to make sure that I have communicated with the owners everything. I would rather them say no than flip a lid later. This has actually built good relationships with the seller if you are a good communicator, which I am.
Also understand there is a large group of "haters" on here that are going to bite everyones ear off and talk about the disadvantages of "sub-2s" and tripping Article 14 in the loan called "Due on Sale" clause. Which talks about calling the mortgage due (pay off the mortgage or we will foreclose) if you transfer the deed into another persons name but the mortgage stays in the original borrowers name.
Study and understand a federal law called "Garn St. Germain Institution Depositor Act of 1982" and learn about Land Trusts. (I will not talk about this here AT ALL)
First off: Even though you are not on the mortgage...Treat it as you are. That means you need every document that they have about the mortgage and the house. OVERKILL is what I would do. Its better to have it and not need it than need it and not have it.
But you at least need the account number, bank the loan is with, payment amount. Also, see how the payments are broken down. Are the payments also with taxes and insurance or separate?
You may need:
"authorization to release information"= Gives you permission to talk to the bank on their behalf.
"limited power of attorney"= extra just in case you need it... you have it.
" disclosure check list"= getting them to sign saying that they understand what you are doing.
"A smart title company"= This is were title companies meet amateur vs professionals. (MUST or NO GO)
If you are seriously consider this... Make sure you know what you are doing on properties and are some flunky trying to make some money and just throwing crap on the walls and hoping something sticks. Go in with a real plan. I dont know you so thats real talk from one to another and am assuming you actually know something about property and investing or I would just skip answering this question.
I hope this is at least a helpful to you.