Vendor Acquisition: Transfer Project Assignments between different company contractor users

One of our Unifier vendors, A(name changed) acquired another Unifier vendor B(name changed). All the active projects under B must now be transferred under A (same users), so that the now A contractor user (previously B) can act on their previous B records, with their new A contractor account which they got post the acquisition.

We were required to create a new A vendor account to resolve their immediate access concerns with new email, etc. due to our access configurations, and since updating the existing B Partner/Vendor record information from B to A would not merge them with the existing A Vendor/Partner record.