Hey there, robbWoods!
Thanks for reaching out in Apple Support Communities! From your post, it sounds like you want to have these devices signed in with your Apple ID for hardware support, but they will be used by other individuals. We'd be happy to look into this with you!
To help the community provide the best support, please reply with the following details:
• Are these devices currently signed in with your Apple ID or the other person's Apple ID?
• Where are you wanting to have them "added"?
• Did you purchase AppleCare+ for the devices using your Apple ID, or do you have questions about insurance provided through your carrier or third party provider?
All the best.