Scholastic released the description for a WellieWishers animated series tie-in book to release in January 2019. It's called Pony Surprise.
"The WellieWishers have just one coin to toss into a wishing well. What should they wish for? Emerson has an idea -- it has four hooves, a silky coat, and a long tail and mane. Her friends love that idea, but they decide to wait until later to make the wish. Emerson tries to be patient, but she wants that pony more than anything! Since they all agreed on the wish, her friends won't mind if she tosses the coin in without them . . . will they?"
I don't read these books because they have the same plots as the show and they literally only have screenshots from the show and one sentence a page, but this listing's exciting, because the episode is one that hasn't been released. Which means one thing:
WELLIEWISHERS SEASON 2 WILL RELEASE BEFORE 2018 ENDS!
P.S: Let's all wish my dad's dog Smores a happy birthday! She's 2 now.