Resize / reposition foreground objects

During the talk, there are usually PowerPoint slides. I can display these using Presenter, with the media in the foreground.
I can also show the speaker by setting the background to video feed
But for those who are viewing the service through streaming (or later through the recording), it would be good for them to be able to see the speaker at the same time as the slides. Currently, this is not possible. To do that, we need to be able to resize the foreground to, say, 25% or 30% of full size and reposition it, typically top right or top left of the display. Ideally, both the resizing and the repositioning should be customisable.