Grasshopper surface modify and uv line

hi, i’d like to transform surface edge to flat

i made some surface and i want made it like periodic surfaces

but there is slit because surface’s edge is not flat

so i did bounding box and made z scale 0 to got plane poject surface’s edge.

i dont know how to transform surface edge

and i got another question
how can sort this uv line? (40.5 KB)