Ok, I get it now, we just have to tell to the network command which edges are the U's and the V's, and select them in rows.

And it works fine with closed edges also, wow.

That's a very very nice tool ! I think it's a bit shortly described in the MoI command reference, maybe a generic guide for U's and V's regarding construct commands could help.

Connected the bottom part with two closed edges, and it seems perfect !