Larry Jordan: Create Multicam Clips Containing Different Frame Sizes in Adobe Premiere Pro CC)
In this "Ask Larry Anything" webinar, Larry Jordan answers how to create a multi-camera sequence in Premiere Pro using clips that are 4K and 1080p. The trick is to create a multi-camera sequence in 4K, and then edit it into a 1080p sequence. Watch the video as Larry guides you through the process of creating the milt-camera sequence, and editing it into the timeline.
Source: https://youtu.be/OEJpFSb-1YY