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.