How do I add sites associated to a different hub to a hub's search scope in SharePoint Online?

So, I have the following problem with searching documents in SharePoint Online:

Setup:

• Tenant

  • Hub A - Agency A Intranet

    • Hub B - Department J Intranet

      • Site M - Division 1 Site

      • Site N - Division 2 Site

    • Hub F - Department K Intranet

  • Hub C - Enterprise Project Management Office (EPMO)

    • Site X - Agency Q Project

    • Site Y - Division 1 Project

    • Site Z - Division 2 Project

  • Hub D - Agency P Intranet

  • Hub E - Agency Q Intranet

The EPMO owns all projects for the organization. My business users project-related documents to come up in their Department's Hub search results.

Requirements:

• On Hubs A & B:

  • Search results should include Sites M, N, Y & Z.

  • but NOT site X or anything in Hubs D or E.

• On Hub F:
  • Search results should NOT include Sites M, N, Y & Z.
• On Hub C:
  • Search results should include Sites Y & Z.
  • Search results should NOT include Sites M & N.
• On Hubs D, E, & F:
  • Search results should NOT include Sites M, N, Y & Z,

• On Site M:

  • Search results should include content on Site Y.

• On Site N:

  • Search results should include content on Site Z.

• On Site Y:
  • Search results should NOT include content from Site M.
• On Site Z:
  • Search results should NOT include content from Site N.

I have found instructions to increase search up in a hierarchy from Site -> Hub -> Tenant, but not adding results from only certain other sites.

Is this possible? If so, can anyone point me to the documentation to set this up?

Thank you!