For more answers to more questions:

Imagine you recorded SubjectID AAA in GroupID GGG using MovAlyzeR.

In hindsight you wanted it to be SubjectID BBB in GroupID HHH.

MovAlyzeR has options to move the data from one SubjectID and GroupID to another one. Just Rightclick on your subject to be moved and select "Move to Group and Change ID" and follow instructions.

When testing at different sites you can set Movalyzer to assign automatically a subject ID to each new subject. Each site can be set to different blocks of subject codes ranging from 000 to ZZZ (36**3 = 46656 different codes). When subjects from all sites are imported into one experiment you will then not get clashes. You can set these in the User Properties >Path & Settings.

If you accidentally do have unwanted overlapping Subject IDs, the import will alert you. Abort the import immediately or you will overwrite data. Instead, go back to the user where the data came from and resolve the undesirable clashes between subjects or groups using "Move to Group and Change ID". Then, again, export and import. Only if there are no clashes, the import will not generate any messages which information will be overwritten by what.

Note that you can assign your own Subject Code (up to 25 letters) to each subject. This code is meaningful to the experimenter. The Subject ID is more meaningful to the data storage than to the experimenter.