If nands are unlinked can I use data management to delete GBA VC injects w/o the system deleting everything?
That is only true if your nands are linked. If your nands are unlinked then you are free to enter and use data management on sysnand freely without anything bad happening.You can only enter data management on emuNAND. Entering it on sysNAND will drop a nuke on your sd card.
You can only enter data management on emuNAND. Entering it on sysNAND will drop a nuke on your sd card.

YesWhat happens exactly? Does it wipe your SD card or something?