school sub portals

I am implementing a site for schools.

There are 5 main categories, such as "Parents", "Teachers", "Students",
"Alumni", and "Informations"

We wanna separate them into 5 sub-portals.

However, there are some information exchanged among each one of them.

For example:
"Parents" sub-portal has their own parent activities, which shouldn't be
seen by another roles.
However, "Parents" may be able to show their members' children's results
which is inside the "Students" sub-portal.
Moreover, "Parents" (and other categories) should be to grab some
information, such as school events and news, from the "Informations"
sub-portal.

The most complicated one is the "Alumni", we need to provide a mechanism to
move students record from "Students" to this category. (it can be postponed
if too difficult)


How should I implment this site? is sub-portal a suitable solution?


Thanks,
Arthur





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