2 Admin profiles on same Mac causing problems

Both Users are set to ADMIN:

User ID Mark has Apple ID associated with it and a specific User in settings; this account has access to all iCloud documents, etc. Since I upgraded to Sonoma in early Oct I get NEW emails from multiple accounts but all saved emails in subfolder are gone.

User ID Mark2 has NO Apple ID associated with it and a different Library/User in settings. This account can access some iCloud files: Photos, Messages, and has all my legacy subfolder emails but Notes is completely blank.

How can I combine Mark & Mark2 files without destroying my world?? Or "move" Mark2 Mail subfolders to Mark w/o iCloud Drive access? I know I can import Mail Boxes but how do I export them in their same format from Mark2 to Mark?

Afterwards should I change Mark2 from Admin to User?