Ladder frame to build dormer between trusses?

[fauer]

I am buying gambrel trusses, and dorming out a section of the roof. Truss company explains I border the dormer area with a double truss at the beginning and end of the dormer. The floor joist in this area go perpendicular to the joists built into the trusses.

I can't quite picture completley the rest of it though, especially the roof gap opposite of where the dormer wall will be. I was told I would "ladder frame" that. I think I finally got the picture...more framing perpendicular to the trusses.... and in each case running from truss to truss lateraly.

Do I have it? How about size of boards/lumber to make this horizontal run from dormer start truss to dormer end truss?
Help!
Thanks

[Rich]

I think you understand the ladder frame assembly. The size of the framing is determined by you roof slope, length of span, and many other variables. An engineer would be able to give you the size.