I have been searching the list of modules to find a suitable solution for a specific need, but don't see an obvious one

I have 50 different groups of people, with just one front end user per group, i.e. all people in one group use the same user login to get to a specific set of pages.
Each group will have a page with their own list of people in their group, with address, e-mail, phone etc. I would like to allow each group to edit their own list on the front end side.
The FormBrowser would have been a good choice, but requires that someone manually populates each groups list through the FormBuilder. If possible, importing initial data to the FormBrowser would have solved this, but I don't see how that import may be done.
So, my questions, with the above in mind, what module(s) could handle these needs? Anyone that have combined modules to fix a similar situation?
Has anyone managed to import data to the FormBuilder/FormBrowser?
If trying to import data directly to the data base tables for the FormBrowser, what tables are affected? I tried to understand the links between the tables, but didn't see it that clear...
Any hints at all would be much appreciated
