I love how you care for your members 
I think this is what will break it in the end 
If you channel all alerts to a single person/group, they will get overwhelmed fast.
Maybe people could have a dedicated “buddy” that gets alerted by the algorithm? That way the burder gets spread out over a larget group of people. And as a bonus, it’s a way to foster interpersonal relationships (I can imagine a lot of messages that will go something like “hey, thank you for checking, I was just on a cruise, it was magical, how are you doing?”).
You will most likely need some out-of-bounds communication channel set up when people opt-in. Because if the worst happens, a PM will likely be ignored by the caretaker. But a direct email might get their attention, a phone call would be even better.