If I am understanding correctly, You have:
Source #1 and aggregated IN THIS SOURCE, are let’s say 10 Entitlements
You then have Source #2, and IN THIS SOURCE, there are no entitlements aggregated
However, Source #1 and #2 are the SAME target system but maybe looking at different information (Main ID, Secondary/Admin account, etc.)
You then want to submit an Access Request for the user Source #2 and give it an “entitlement” that exists on Source #1.
If this is true, then I don’t see how this would work natively since the generally rule is that the entitlement IDs (which is what you would need for the access request) is TIED to the source that aggregated it.
I have not seen where I could add an entitlement to source #2 that it had no record that that was there or available (because its not looking real time at that source but looking at aggregation data to know whats there, whats request-able, etc).
Let me know if this simplified version of what you are looking for is not correct and I can dig deeper.