Have you thought of advertising a trade? I really have no concept of how it would work but in your shoes I might consider figuring that out. Offer to trade for a larger house with you making up the difference in cash from the sale of your Mother’s place. If you find somebody, pay a Realtor a nominal flat fee to help put it all together.In this market it might just work. Rumor has it builders are doing it(more or less). If you get the right place it is easy to modify it so that you mother has a private entrance and a little kitchenette if that is desired.
Disclaimer: Consider this along the lines of shoot from the hip brainstorming.The idea is that you have already lost your downpayment if you sell and all parties will avoid big commissions and perhaps get into a more suitable situation.Somebody out there must want to downsize but is facing the same problems in the market that you are.
