I'm using CiviCRM mainly for membership signup (in wordpress). Now I have created a profile (a custom field set) to ask for extra info upon member signup (the signup happens via a contribution page). Now some people in the organisation should just be able to edit the data in the custom field set (so not the contact), but whatever combo I try for wordpress roles and CiviCRM ACL setup, the only thing I can achieve is that people are able to edit all the data from the membership (also signup date, end date, member statys etc ...), but not just the extra info alone.
So any hints on this (if this is at all possible)? I also looked at the API calls, but those don't seem to cut it either.