Token Slider Player Additions

So I'm playing in a game where I'm playing a shapeshifting character that can only change into those I've seen. Is there a way for my GM to give me the ability to add those images/tokens myself without him having to make a new token each time and put more strain on him? Just curious is all as I don't want to turn into things I haven't seen yet so I would like to actually be able to add to the slider anytime needed.

The only easy way for you as a player to do that would be to use a Mod script, which would require the game creator (GM) to have a Roll20 Pro subscription. With Mod scripts it's very easy to create a macro that would let you add image sides to your current PC token, using a script like TokenMod or Faces. And just thinking out loud, if you created your own multi-sided token in your own game and saved it as the default token for your character there, you might be able to import it back into your current game and use it that way without having to bother your GM, but I might be forgetting some detail that would prevent that from working, and I'm not able to test it out myself at the moment.