ZBrushCentral

Properly merging and fuse 2 subtools

I have 2 subtools, the whole body and the hands. I want to fuse them.
Dynamesh is not an option, I dont want to Zremesh all over again and then project all the details of the whole body.

I merged down the 2 subtools, they have 5 subdivisions levels, I cant delete them because I would need to project the details again and that isnt an option neither. Cant use Curvebridge brush between the two meshes because “The mesh is composed of multiple subdivision levels”.
Tried Bridge two holes from Zmodeler too, but I cant work with all the subdivs neither.
Tried to freeze subdivs, working on the lowest one but when I go back to level 5, mesh doesnt work well

What can I do? I cant find the solution for this

Zbjgx2E.jpg

Does remesh by union work?