Handling Acquisition

As a part of the acquisitions, github instances are having different user names as per their Organization Standard, (Example: E-Mail address, LoginID, Display names etc). Where as in most corporates, SAML / SSO users would have a standard login id, E-Mail, Display name etc.

Once we integrate GitHub to Corporate SSO, is it possible to Map the users SAML id to the github’s old id or the users will have continue to use only the new SAML ID.

Example:
Old GitHub id is: Mike
New Corp SSO id is: msmith

After GitHub is integrated with Corporate SSO, would it possible to map msmith to Mike and the user can continue to use the ID Mike or the user will have to start using the new ID msmith.

I found this link on Support:

The SAML IdP and the SCIM client must use matching NameID and userName values for each user. This allows a user authenticating through SAML to be linked to their provisioned SCIM identity.

If it is not possible to use the users OLD id, please let me know if there is a way to Integrate the acquired company’s github instances to SAML / sso in a seamless psaaion.