Single document with varied access.... possible?

Can we achieve the following "membership" scenario with some customizations if necessary?

User1 (of Group One) creates master record, a multipage form that includes 3 pages of text areas, checkmarks, dropboxes etc.
User1 selects User2 and User3 and provides access to the form.
User1 (above) can modify page 1 only.
User2 (of Group Two) , can modify page 2 only.
User3 (of Group Three), can modify page 3 only.
Site visitors can search and browse all records.

NOTE: User1, User2 and User3 are paid subscription members.

Hi

Unfortunately, it is not possible. I am afraid of you will have to do some customization in this case. The biggest question here is that what extension will you use to create the multi-pages form you are talking about ?

Tuan