DECODING-SPACES doubts

**Hello guys, I am wondering if anyone can help, I am starting to use the plug ‘‘Decodingspaces’’ **
I’m trying to make a urban site, but my problema is about that I can’t make my parcerls in a specific measure (as the purple square). How could do that? I know when I move an initial street segments, it changed his measure but are there any way to keep the measure square that I want?

Big thanks.