You can edit the .inp and .net files, if the node and pipe names are not duplicated then pasting one input into the other should work
then you would build the inter-ties. As for the .net files again you would have to verify they do not overlap in the map
Yup--no simple way to do this one as EPANET has limited editing abilities. What hydrae said above will work, but be careful that they do not overlap (as stated).
I don't know all of the functions of the software, but I've used EPACAD to pull AutoCAD files into EPANET. It's limited, but very handy. I don't know if it has any functionality with actual EPANET files since I've never combined two before. Might be worth a look, but I think it's mainly for pulling AutoCAD into EPANET.
