ROM Hack Pokemon black - Adding new (Not replacing) Sprites?

[Flintiex]

Say I wanted to add a new 'overworld set' of sprites to the game, but didn't want to replace any of the current overworld sprites already in the game. Would it be possible to add new sprites without replacing any of the existing ones?

 

[KingDrapion]

I dont think so... But if you can then I dont know how to do it