Maybe I'm not real internet saavy but I looked for two days on the internet for my MMSI number with no luck. I was trying to find it ti give out if anyone wanted it. I could go to BoatU.S. and look it up but I needed the email and password I registered with it at the time 4-5 years ago. I could find databases with MMSI #'s for ships with FCC licenses but that was it. I called a friend at the marina and had him go to my boat and get my number from my radio. He did get it for me but no one has asked for it or wanted to trade #'s.
And as far as the group MMSI #, I'm not sure how that works. And my Northstar equipment only allows you to track up to 3 "buddies" at once. If any one wants to trade #'s for tracking purposes, please PM me. I still would like to give it a go.