Converting polylines to polygones on PCSWMM

[StephP]

Hello,

I am working with data which has been gathered prior to me. The subcatchments have been defined as polylines, which therefore does not allow me to define the area of the subcatchments, and co (though surprisingly I can import the shapefile without any problems with PCSWMM). I would therefore like to know if there is a way of converting my polylines to polygones.
And I would also like to know if we can have more than one layer for each SWMM component: i.e. have 2 layers for 2 different subcatchment resolutions, different conduit layers depending on the type of conduit (open, closed, for drinking water or wastewater, etc.), and so on. Or do I have to put every similar information on one single layer??

Thank you in advance for your help!