Background Pony #1072
In a couple of previous discussions, here and here, these two tags were suggested as being differentiated by shared involvement of someone vs. just line-of-sight or mental involvement - ie. two siblings each having sex with their spouses in the same room, or voyeuristic masturbation while spying on a family member, vs. relatives physically interacting with the same single 3rd party although not touching each other.
Are those still concepts worth keeping separate, and if so, are semi-incest and indirect incest the tags to be used for them?