Hello
I'm surrently remodeling our bathroom and I would to like modify the existing flooring before tiling with ceramic tiles. The existing subfloor is 5/8 plywood. The underlayment was 1/4" plywood, which I have completely removed due to water damage. What plywood (thickness) should be added to the existing subfloor before I install a final layer of 1/4" CBU? What are the best fastners I should use to secure the additional plywood underlayment and the CBU to the subfloor?
Thanks!

You can go back with 3/4 as well as 5/8 then 1/4 tile backer, and we use screws to fasten the flooring back, 2"