Ahhh I understand! So the library itself keeps what you’ve downloaded anyway, and when you go to select it in your bridge it will show you have it and just need to import it. To change this library’s path, head to your preferences in bridge:
then change the path to the new location.
move everything in the old location to the new one, then when accessing bridge again it will always pull from the local library first, then look online if it doesn’t have a copy of what you are requesting.