Membership Plugin (Premise)

Hi,

OK! So here is what I am trying to do! I have purchased a membership plugin called premise. I am looking to add this type of functionality. When a member registers for my site, I want them to input their zip code along with other standard info. I want the plugin to create groups of 15 members per group. They should be placed into groups by their zip code. Meaning, the first 15 members that register for the site with the same zip code or a similar zip code (within a 30 mile radius), will be grouped together. All groups will be groups of 15. After a group has 15 members with the same zip code or a similar zip code, the plugin will create a new group.

Is this possible?
Ideally, I’d like to stick with the Premise Membership plugin, but is there any other membership plugin with this functionality?
Are there any plugins that I can add that will give me this functionality?

All help and advice is appreciated! Thanks!