Ajax Tabs on profile page/Multi form submit button

hi,

I am building a site where each user can have sereval different types of profiles.
A user can choose which profile he/she wants to create and can delete and/or add profiles afterwards.
The design and workflow requires that the user switches between the profile editing pages without submitting.
So the User should click on a tab, edit the first profile, click the next tab, edit this profile, go back to the first and so on. In the end he/she clicks a submit button to save everything.

My first attempt was to use just one profile content type and do the tabbing with cck_fieldgroup_tabs. This works almost as planed. The only problem is that some of the fields (multiselect text fields) should be present in all or at least several "profiles". This is, as far as I know, not possible because one field can only occur once in one content type.

So I can think of three sollutions:
1. make the tabs on the profile page ajax-switchable and with one submit button.
2. make it possible to put one field multiple times to one content type
3. put multiple fields to the content type that have the same settings but are technically distinct.

The only thing that I know how to do is the last one but that would be a maintenance nightmare when the entrys in the text selection change.

Can someone help me with this?

Thanks in advance
Angel