Screen sharing webcam size

Hey! I have already asked this question in this other thread, but it sure wasn’t quiet the right place.

I’m hosting Jisti Meet on my own server. I understand that the screensharing-video and the webcam (if webcam is activated) are mixed together on the server side and send out as one stream.
Please point me to the configuration/file/variable where I can set the size (and maybe the position) of the webcam in the stream.

As mentioned in the other thread, in a Webinar situation the size of the webcam is sometimes to large and covers too much of the shared screen.