custom weapons

This is epic but I have a question regarding that: let's say you weapon in the ROM is displayed in diagonal. I don't know how much space a weapon sprite occupy but let's say he occupy a square when you view the graphic in YY-CHR. His maximum length is the diagonal of the square. If you want to import/replace with a bigger or longer weapon sprite, how do you do that?

It would somehow shift the data and you would need to change all the pointers relative to the subsequent data unless data unless you overwrite part of another graphic... So is there a way to replace a sprite with a bigger one without much consequences?

Edit: The answer is probably no but maybe there is something I didn't get...