You can actually have up to two casters who can summon Shovel, even at the same time if you want to! It’s not even a big or a glitch. Just have the other caster talk to Shovel and she’ll give them the ability to summon. I think it would be a fun and interesting contrast in dynamic to have a cleric be “cursed” with a chaotic quasit. And maybe some day find a common ground and understanding with each other, roleplay wise :)