Connecting two Section Geometries

Hi all,

I am trying to build a geometry of a bridge cross section (with multiple girders) and a deck to have a final geometry of a superstructure.
I have created the geometry of two structures separately in Teddy .dat file and imported it via readcdb command. However, I have hard time connecting those two structures together.
So far, I have used Composite Section command; however, in this example I made the number of girders variable, hence, I do not know exact midpoint of the deck so I would use it as a refPts in CompositeSection command.

I was wondering if you could give me any suggestions which command can be used to connect two sections through specific points?