Have a look at this older
post.
In cases similar to yours we organise hierarchy of communities/groups, where pages common to several groups are located in the 'parent' group.
For example, department has many project teams, everyone in a department has access to 'department' group/community, then each person may belong to one or more project-specific groups.
How to show/navigate to those pages is a matter of your specific context and usability.
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