unless you know what you’re doing you should always insert things in free space
Do not delete anything, overwrite instead. deleting anything in the rom effectively breaks any pointers that point anything after what you deleted. It’s better to just use free space.
People are moving away from using feditor because of stuff like its data management system.
I recommend looking into the newer EA buildfile method so that you don’t have to worry about feditor breaking things.
EA is currently the best method for inserting while managing your space right now so i suggest you try using that since there are tools that cover basically everything feditor can do.