Prior to anything....THANKS to all.
Now I have doubts, not problems.
1)  What happen to the backup copies that I already have of a file under
another mgtclass ? Do they become deleted once the file changes mgtclass ?
(off course the # of versions is less or zero)
2)  When you suggest backup you mean backup in general (any type) or
incremental only ?
3)  SO, there is NO WAY to delete a SINGLE (unwanted) file(s) from an
ENTIRE filespace ? I think ADSM needs here a big improvement.

Thanks again for the inconvenience.