I have concerns that multiple_handjob (and multiple_fellatio, along with any such others) are not intuitive, used to tag images of one subject performing these acts on multiple others, rather than multiple subjects performing such on a single target. Further, such imagery is often enough tagged with "teamwork", which leads me to think that "team_handjob" ("*_fellatio", etc.) would be clearer in their use (outside checking the wikis).