I feel your pain, kind of.
When my dad died in 2012, I handled his estate. Mostly this meant liquidating his cash. I took over his bank accounts and cut checks to my brother and myself for half each. Couple thousand dollars for each check, two checks for each of us. Not untold riches but a nice chunk.
So now jump to about 2 years ago, one of the banks calls me to tell me that my brother never cashed his check and it's about to be sent to unclaimed property. I call him and ask why he never cashed it. Never got around to it. Why should I care, it's not my money. But I handled the estate so the bank actually refunded the money to me, which doesn't even seem right.
So then I call the second bank about his second check and they say oh, you just missed it. Sent it to unclaimed property about a month ago. Well thanks for the heads up. So my brother is not good with paperwork so I get the forms and fill them out, get his signature with the notary, send it in. So he gets back a letter from another department saying they need more proof of ID or something. And he hasn't responded yet. And it's been another year or two.
I mean why should I care other than I started the whole process and I hate to see money get lost. But I'll probably have to take him to the bank or notary again.
I can relate to that problem from a different angle. Three decades back my paternal great-great- grandfather passed away. My father and great-grandfather had already passed away. Thus their share of the estate should pass to myself and siblings. My aunt got herself appointed estate executer and proceeded to rob it for everything possible. At the time we had no idea that we were due anything. It was only after she was sued by my other uncles. She went to jail and forced to pay the estate back. We received about ten thousand dollars apiece. Your brother should be thankful.