Finally found the solution!!!
(I had to edit osso-af-init/af-defines.sh and change MyDocs-export to the new name.)


NOW THIS IS THE NON PLUS ULTRA Repartition!!!

1) Minmal invasive (only exchange vfat and ext3 partitions!)
2) Little changes (in genfstab, ke-recv and af-defines.sh adapt exports to the knew name.
3) Applications work like before
4) /user/home/MyDocs is now a regular directory on the big partition (OVI-Maps works on this partition)
5) The vfat partition has a new name and operates as USB Mass Storage.
6) Everything is easy to revert.
7) NitDroid puts data in vfat partition.

Everything I wanted! Everything revertable! Everything easy!
... and much room for linux and applications and their data and multimedia!