We are having a discussion about a certain subject and one of the participant who is physically present has an idea which he needs to articulate to the others. He automatically looks for the best tool to do so and in a meeting room the most natural thing (and easiest) to use is usually the whiteboard. So he jumps off his chair and starts to illustrate his reasoning to the other participants using the whiteboard. As some participants are in the same room, he does not only choose to communicate via a tool that the participants joining in from elsewhere via the web conference does not have access to, but he also forgets to tell the participants that he is now going to use the whiteboard to illustrate his reasoning. At this point, the meeting facilitator(me) should probably make the person aware of that some participants cannot see the drawings on the whiteboard. But since doing so can also disrupt a creative process, it is something that needs to be handled with care. My choice was either to disrupt a creative process and a communication process that worked very well for the participants physically present in the meeting room, or to leave the other participants wondering what the heck the person was talking about.
What I did? I let him continue a short while until there was an opportunity to remind him about the participants joining in remotely. I also quickly made a simple sketch in PowerPoint of what he was writing on the whiteboard that I shared via the web conferencing tool. After having stopped him, I asked the remote participants if they had followed his reasoning (they answered "so and so") and then I made a short summary of it myself using the illustration in PowerPoint which they all could see. We could then continue the discussion using the PowerPoint sketch that I shared via the web conference.
Another more practical thing which is complicating the communication in a semi-virtual meeting is that the participants who are physically present won’t call in individually to the web conference. Instead they will all call in using one person’s identity and then put the speaker on. It wouldn’t work if all of them would call from their own phone or computer. But, when they share one person's identity it becomes harder for participants who are joining in remote to know who’s saying what in the other end.
To sum up; having semi-virtual meetings requires structure and discipline to follow that structure for all participants. Participants who meet face-to-face must always remind themselves that some participants are joining in remote and seek to use the communication tools which they also can use. This can in turn be a constraint to creative processes. So, to support creative processes it is even more efficient to have virtual meetings than semi-remote. Meetings where creativity is a key necessity to produce an outcome, it is probably better for all participants to meet face-to-face.