I was under the impression that you wanted to use a surface to control a curve. I am now thinking you are wanting to have on poly surface nicely next to another, is that right?

If so, you can duplicate your first object, hide it. Then do the same with you second object. Use a boolean operation then try to use the split poly tool to make sure you stay all quads. Move that new piece of geometry just out of the way then unhide your surfaces. Do another boolean but in the opposite order then use split poly to ensure quads.

What is it you are trying to make? Do you have a screenshot (that would help)?

If anyone else is thinking of a better way, please chime in.