If you go to solo mode ( makes it easier ) then ungroup , hold the Shift and Ctrl keys then right click on the area where you want to select a mesh. A menu pops up with just the meshes in that area on it. You don't have to hold the shift key, but by holding the shift to you don't have to worry about losing the meshes already selected. You can also do it by left clicking but then you take a chance of moving something already selected by mistake.

Stephen Ray