Have a weldment from 3D sketch of 2" tubing, how to add 1" tubing to it?

Hi,

I've got a weldment frame of 2" square tubing built from a 3D sketch using a structural member.  When I try adding a second structural member with a different tube size (1" square), the tubes don't get cut where they intersect.  Whats the trick to mixing different size tubes?

Thanks!

SolidworksWeldments