Tom,
I have also filled out the contact data for the VHF MMSI and the EPIRB but had not given any thought to what I wanted the "contactees" to do. I assumed, perhaps incorrectly, that the reason for the contact is to allow the responders to verify that the alert is real and the data correct. That is, Yes we do have a sail boat and yes it is likely that we are 140 miles off Georgia going north in the Gulf Stream, and this isn't a "crank call" false alert. What I want them to say to the Coast Guard is, "Yes this is real, please go find them......"
On another point, in my limited experience I have seen almost no value in VHF MMSI#. The range is short, most boaters don't know how to use it, the Coast Guard doesn't seem to trust it. I would turn it on as I abandon the boat. AFTER - I had done the MAY DAY call. A MAY DAY seems to get everyone's attention. It is seriously abused, but it does get attention.
Thanks,
George
S/V Delicia