The key to figuring this out is to remember that both the PMVS and the PMR1-7 are both equivalent to a 206 module in the aspect of counting extension ports. They are both worth 6 ports, activated or not. The major difference between them in how the ports are activated by their respective port license cards.
A couple of items of note:
1. Most PMVS modules have 2 ports active out of the box, no port license card required.
2. PMR1-7's REQUIRE a port license card in order to work in production. If there is no port license card in a PMR1-7 the system will report "Welcome to Partner Messaging. This unit is in test mode" only. It will not answer calls the way that I am sure you want it to! A PMR1-7 will report this if the port license card is not seated properly and/or if the card has gone bad as well.
So, on to determining what ports to add to Group 7 in your Partner System.
As an example, let's say that you have a 5 card carrier and in it you have an ACS, 2 206 Modules, and a 2-port Partner Voicemail Solution. That would look something like this: