Re: minimalist family and out of control grandma buying?
I can really relate, although our situation is a little different. Buying too much unwanted things can be frustrating enough but your moms sounds like she has a problem beyond that. If they really can't afford to be spending all that money I would probably talk to your dad about limiting her spending $$. He doesn't need to be struggling to make ends meet when she's filling up rooms with all this stuff.
If that didn't work I might try reselling the items and giving your dad the cash. But personally I really think he needs to cut off her access to their main bank account.