How to add another icloud account to my mac without syncing to my present icloud account
I want to add another persons icloud to my mac and I don't want it to sync with my icloud account. Is that possible. Can you help me with this please?
Only a single primary Apple ID of an administrator is signed in Mac system presences , however another Apple ID address can be added in the primary account from appleid.apple.com About your Apple ID email addresses - Apple Support
See the section - Add an additional email address
This will not sync your iCloud data in a condition when you don't reveal account credentials to the person .