A thestral, a siren, a zebra, a dragon, a changeling, a kirin, three unicorns, three pegasi, three earth ponies, and three alicorns all walk into a bar.

They then get kicked out because that's way too many characters with "primary/secondary protagonist" billing for one story.

But despite admitting she could stand to thin the numbers just a little, the author is also incredibly stubborn and sentimental and isn't inclined to let go of most of this cast.

This could be a problem.