Looking for freelance middle grade writers for a book series

I'm looking to add 3 freelance Middle Grade (MG) Horror/Thriller/Fantasy writers to add standalone books to an existing series (think Goosebumps meets Stranger Things).

This is a 10 week freelance position. At the end of the 10 weeks, each of us will contribute a standalone book (18,000-22,000 words) to the series that will connect to the overall theme.

Each writer will be paid $100 (upon completion of expected work -- which is mapped out in the contract you'll get if chosen as a finalist) and each book will also get a designated marketing budget from me to market their book and then there will be a royalty share of all of the books from this group of books in the series.

I will cover all costs associated with publishing: beta readers, editors, cover designers, and final publishing costs.