i read throught the post so far and they seem reasonable.
He should be able to consult with an attorny with out going broke, and then go from there to decide if further action would make sense, but just like any service the attorny deserves to be paid for his time.
I think the biggest point i want to make is, that while yes it is worth pursuing this to a point, (since there already isn't a strong family bond, it doesn't seem like that matters. to me it's more how much upfront money and energy does your friend want to put into this.) how far you pursue it depends on what the lawyer finds out.
What bugs me a bit is that it sounds like Frank is the one caring for and dealing with elderly alcoholic mom, who probably isn't a picnic in the park to deal with. i always feel the sibling that is caring for the parent deserves more in compensation. but not knowing the whole story maybe there is more to it.
I guess what i started to say was that your friend in essence never had this money and shouldnt' get his hopes up that there is any left for him. that still isn't what i mean exactly, maybe don't count on it to change his situation, he should be working hard and making good decisions so that good things come to him by his own accord not from this dysfunctional family. Still not quite what i mean. I hope he does check it out and i hope there is some for all, and i would love an update someday.