I don't rely on the registration site for per-trip info.

I fill out a trip plan and send it to my contact so that when the authorities call her phone number when I activate my PLB she will give them the trip plan and info describing my capabilities. She also as instructions as to the time I suggest she contact the local authorities as well as who they are as part of my plan.

I think this is much more likely to be effective - and it gives my wife's aunt something important to do. (She's a very competent lady)