Rather than just preaching conservatorship, conservatorship, conservatorship... any ideas on how to simply block the calls from getting through? Conservatorship won't work for a lot of people, especially when the only apparent problem with some elderly persons is that they keep falling for this scam, sending money, etc.
I've read about various products - Caller ID Manager and others - but most seem to either be discontinued or don't work with landlines or have some limitations.
Another - ColdCallBlocker - supposedly allows you to block incoming calls for an entire area code (876 is Jamaica). But apparently they don't have a landline version.
Ideally, if one can simply block the incoming calls of the scammers, at least some - even if temporary - relief can be achieved.