Possible Subto deal that I am looking for guidance on.

[Joseph Micah Chmura]

I am seeking guidance on what I believe may be a Sub to situation.  My brother brought this to me, and I am not the actual person who would be buying this home.  I am trying to help him out, as I am the RE investor in the family, but I have never done a Sub to, just house hacked.  The property owners need to sell ASAP so they do not have to pay two mortgages at once.  House has been on the market for almost 40 days, and their time is running out.  They do not want to rent it out and are willing to rent to own to my brother possibly.  But I told him it might be worth doing a Sub to with them because they don't want to rent out.  They are about even on the property with equity.  It might be around 20-40k on the house worth around 440k, which they would lose with closing costs and realtor fees if sold.  The win-win for this situation is that they get out of the house before paying double the mortgage, which they can't afford, and my brother would take over a pandemic interest rate on a 1-2-year-old home.  What advice would you give for structuring your first Sub to deal with someone who seems interested in just off-loading the property without taking the significant loss of income from two mortgages, and what are some pitfalls that I wouldn't want my brother to overlook?  Im tracking the bank can call the note due, but there are ways to get around that by deeding the property back to the owner and then back again.  Any help would be appreciated!  Thank you!