<human>: Can you give me the gist of the text in a nutshell?

My father is in his mid-50s and over the last several years has developed progressively worsening Frontal Temporal Dementia.  He pretty much lacks any sort of response to social norms or behavioral cues from other people, has severe aphasia, and has difficulty following or understanding conversation.  As of this Monday, he has surrendered his license.  When he gets an idea into his head, it tends to be persistent.

My uncle, his brother whom we'll call John (as that is his name), has been a leech for pretty much his entire life.  He was the youngest of five and had an accident when he was young, so he was coddled for most of his life, and is now in his early 40s and has a kid who's 14.  

I don't know what John does all day, but whatever he's doing, he's pissing away money at a crazy rate while barely working.  What he does do is call my father and hit him up for money saying how much he *needs* that money so much.  The bastard's persistent and manipulative and wrangles hundreds of dollars out of my father.  My father cannot see that giving John so much money is ultimately incredibly destructive to my family and the people that my Dad gets money from.  Apparently my Dad keeps trying to get my other uncle to give John money, has gotten money from his friends to give to John, and gives whatever my mother's given to him over to John. 

What can we do to prevent my father, who is very insistent, but also not reasonable, from giving money to my uncle?  Things might improve now that he can't drive to see him, but that won't stop John from continuing to call and harass him about it.  My father says he wants to work now, and my brother thinks it's so that he can earn money to give to John (Related note: if you have ideas of jobs people with dementia can do, I'll take them too).
<bot>: My uncle's a leech and pulling hundreds of dollars out of my father who can no longer think reasonably.  How do we stop it?