I have a problem with Attach, Rebuild, Detach surface.
 

When I want to build the detail of the surface, at first I detach the section of the surface that I will use to add more details and I use like duplicate curve surface to make the same shape of the isoparm on the surface but when I modify using Boundary tools and rebuild it ...the shape of the modify surface started to change a little bit so it didn't match to the surface where it detached from...I try to attach it but it is not a good way because it didn't turn back to be smooth as before even I have already use Global stitch but it still have some gabs.... is their any other way to make the modify surface to fit to the neighbor surface as before?