Basically yes. But with two/three considerations.
1) For the satellite receivers (HDS and another one feeding the Solo). You should use a 4 port LNB on the satellite dish. This is so that each satellite receiver can separately select horizontal or vertical polarization according to which channel is selected by the users. I think this is your idea.
2) You need to ensure the two sling devices to use different port addresses for their streaming. For example, one set to 5101 and other 5001.
3) Your internet upload speed may limit the received picture quality, due to both slingboxes sending much data at the same time.
I used to have an HDS and slingbox pro installed at the same location. Once set up correctly, they both worked fine, but the BT internet upload speed did restrict the received picture quality when both were streaming at the same time. The arrangement was same as you wish to do, only I was using slingbox pro, not a solo.