This may be the moment we have been waiting for... The CBsubs is ready and from the description I read it should do what we are after. Here it is:
Provider - Consumer type use cases
You can use CBSubsTM to provision various provider-consumer type sites. Example: student-teacher sites where teachers and students have different tabs/fields and student cannot see other students grades but teachers can see all student grades. Model-agency sites, where agencies have different profile tabs than models, models cannot see other model pictures but agencies can see all model pictures. Also extra pay may permit models to upload more pictures. There is alot of flexibility and you should be able to make CBSubsTM work for your specific use case.
here is the link
www.joomlapolis.com/content/blogcategory/61/74/
Has anyone tried it yet?