Exchange provisioning for select users

Question

Scenario:
Users in Set 123 need AD accounts only
Users in Set B need Ex mbxs (& AD accounts obviously)
Users can move from Set 123 to Set B, or go directly into Set B
We cannot simply create a 'base' AD sync rule, and then a dependent Ex sync rule with homemdb,mail,msexchhomeserver &mailnickname - we cannot use 'initial flow only' in a dependent sync rule.  We don't want FIM to continue to set the msexchhomeserver
and other attributes - we want to transfer authority to Exchange to manage those attributes.
If we create two separate sync rules, not dependent, we can't control which tries to execute first.  If we have the ex sync rule with
just homemdb,mail,msexchhomeserver &mailnickname attributes set for initialflowonly, it will fail if it tries to run before the sync rule that creates the AD account.
Separately, does initial flow only run when the user is added to the scope of the sync rule for the first time, or when the object is actually provisioned in AD?  In other words, if a user object exists in AD and FIM is aware of this, will FIM flow
out attributes in a sync rule set for initial flow only?
Ben Pahl

Answer 1

We solved this by:
Flowing in AD Base sync rule inbound mail, msexchhomeservername,homemdb,msexchrbacpolicylink,msexchmailboguid, mdbusedefaults & mailnickname
Creating equal precedence for all of those attributes with FIM Service *being careful to never run a full import/sync from FIM Service and then immediately exporting to AD, without doing a full import/sync from AD first* 
Creating a set that says: *you are supposed to get an exch mbx based on job codes X-XX, *you don't have a value in your msexchmailboxguid currently, *your hrstatus is active
Creating transition in MPR to the above set that fires workflows.  some workflows stamp static values (homemdb value, msexchhomeservername, etc) to the user object in FIM service.  some generate unique values for things like mail and mailnickname,
and stamp them on the user object in fim service
The MPR above also adds the user to the scope of a dependent sync rule that does not use initialflowonly for the referenced ex values above.  they flow out from fim service to metaverse, then the ex extension provisions the mbx.  when the user
transitions out of the set above (they now HAVE a mbx, so they move out) they are removed from the scope of the exchange sync rule.
Ben Pahl