Can I sync in this way?

Hi. I have a multi-site installation. A main site and several sub-sites. All registrants of the sub-sites are automatically added as users to the main site but not the other sub-sites. It is possible for a user to be registered at more than one sub-site. I'd like to sync in the following way:

When a user makes changes to his/her profile on a sub-site the main site should be updated.

When a user who is a registrant on multiple sub-sites makes changes to his/her profile on one sub-site the main site and any sub-sites which share the same user should be updated.

Is this possible with WordPress User Syncronization? If not, is there some other way to accomplish it? I would rather not use BuddyPress as I am not well-versed in it and I don't think I have any other use for it.

Thanks