Subdividing Boundary Surfaces Troubleshooting

Hi there,

I'm a grasshopper beginner and always find a lot of good information in this forum. As I got stuck now, I post my first question hoping for answers!

I'm working on an architectural project and want to subdivide parcels into building plots of 6.2m x 20-25m (please see screenshot an gx file attached). I managed to do parts of it already, also with the help of this discussion, but I have 3 problems with it:

-When I try to extrude the subdivisions, some of them are not extruding. My guess was that all line-like curves work well, but not the linear curves. I exploded the linear curves and it changed something but didn't make it better.

-When I use two parcels as an input, it doesn't work anymore (even though both result in untrimmed surfaces).

-Some curves result in trimmed surfaces, so I got problems with divide surface. I read a lot of discussions on that but couldn't really find I way to solve it.

Help would be really appreciated!

Best,

Valentin