The MySite "My Memberships" Web part searches for users in the
[SiteName] "Members" Group.

I understand from the following post that these are groups with the
vti_associatemembergroup property set.

blogs.devhorizon.com/.../45
8.aspx

Because the reccommended best practice for creating new sites is to
inherit from the parent site and later break the inheritance to add
groups, I have several sites set up with their own security group.

SITECOLLECTION (SiteCollection Member Group)

---- Inherited Site 1 (SiteCollection Member Group)

---- Site2 Broken Inheritance (Group [Not Member])

Members of Site2 don't see their Memberships because their groups don't
have this property set.

1) Is there a tool to set this property after the fact?

2) Can I Associate multiple security groups as the membership
groups to the same site?

IE

SiteCollection) Site Collection Members

Site1) Directors Group, Staff Group

Site2) Accounting Group, Directors Group

I want Directors, Staff, and Accounting to all see their associated
sites from "My Memberships"

3) Should I create an event to double-enter the accounts: every
time someone is added to a subsite group it also adds them to the Member
group?

4) Does "My Memberships" expand A.D. Security groups so members of
that group see their associated sites even if they aren't explicitly
listed?