BSP Merge Verts Issue (question)

Does anyone know why the faces get split when I merge verts? Or how to get rid of the triangulated face when merging verts? thank you.

It’s probably because the vertex below the one you’re merging is not aligned with the top vertex after being merge. My guess would be to ensure that the edge is aligned before merging or see if there is a way to merge the edge instead of just the vertex. BSP faces are always triangulated like that in the engine, as graphics cards only render triangles. What’s breaking is the UV coordinates, so you could also try fixing that. Generally it’s a bad idea to use BSP to this extend.