Custom loot table when breaking spawner

Hi, I've been making a custom datapack, which (including other things) allows me to craft spawners and spawn eggs using netherrite. 
I want to be able to break and collect the spawners so I can move them around (because they're quite expensive to make). Getting the spawners to drop was pretty easy, but I'm having trouble with getting it to drop the spawn egg that was used on it. Is this possible? If not, another alternative could be to make it drop the netherrite needed to craft the spawn egg, but then you would have to somehow check if the spawner has already been activated with a spawn egg, and I'm not sure how I would do that. 
Any help would be appreciated!