Reordering thumbnails on recorded gallery view zoom

Hi,

I am a novice with Premire; I have done two or three college projects using it, but I currently work in the theater department in a high school and we are figuring out how to put together a play online. We have zoom recordings of the students all acting together (we don't have them recording individually and sending in each clip because we still want them to practice reacting to eachother, though I know it would be easier to create split screens with seperate recordings) but in a couple of clips I need to move some of the students. This is essentially a question of splitting a single frame and moving two rows of students onto one row, and then putting that now smaller and longer row accross the top of the screen. This isn't possible in zoom itself because participants are ordered randomly, and evenly disperssed over a full screen. If anyone has any idea how I could simply split my frame in half, top to bottom, and then move one half up beside the other half, so that I can have another image of student art running below, I would be incredibly grateful. When I try to google my question, I only return results with how to make split screens with lots of different recordings.