Some preparations before I attatch the three surfaces together.

I have inserted isoparms at the edge of the other two parts, so that the attach option doesn't give me a wierd shape.

I guess I inserted too many isoparms here, but I'll go for it.

Another thing; I also inserted isoparms in the other direction (along the model) on the two backmost surfaces, in order to give them the same number of spans as the front surface.