Hey there TJRealtor,
Since you can only use one Apple ID at a time, you'll need to sign out of the extra Apple ID. Since purchases cannot be transferred, you can still share them between the accounts. Family Sharing will help with sharing some of your purchases or information. Learn more in the resources below:
What is Family Sharing? - Apple Support
Set up Family Sharing - Apple Support
Regarding your Watch and Messages not working, can you provide further information about the issue? Are you seeing a specific error message? The more details you provide, the better we can assist.
Take care!