Perhaps you should try this:
From what I see It would be easy to build up each window section from three seperate sections. Two square ones(for the bottom two section) and one rectangulair one(for the small shape left in the top), hope you grasp idea this so far...
. Otherwise you might want to refrain from reading any further...
Here comes the trick...rotate the sheet brush so it kinda aligns to where you would like the window to be
Turn on pivot snapping, and turn off the grid(be carefull with this and don't forget to turn it on later). Select a vertex from the sheet brush by -left clicking- on it in the 3D window, I advise to start with a bottom one.
If you hold down the -left alt- button, you should be able to move the vertex by dragging you mouse while holding down the -left mouse- button. (If you're familliar with the controls you should be able to move the vertex in the 3D window as well).
Now try moving the vertex to the matching curve in your spider architecture. If you get it close enough it will snap to the curve.
By moving all the vertexes this way and snapping them to the matching curve you should be able to get, clean, seamless architecture.
Once you have one part finished simple duplicating mirroring and rotating should do the rest..
OK, I know sounds a bit difficult and it's pretty hard to explain this fairly simple process this way
but if you know how to do this you will probaly find it to be a usefull trick in many other cases.
Hmmm...visuals....