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Shafqut most export functions do NOT layer mult streams into one view. The main reason is when you export the videos they are full/high resolution and placing mult views into one window would require them be scaled down, which negates the purpose at hand normally. Provide them each view as its own file. There is no need for them to see all views on the same screen - they should be inteligent enough to follow what is happening by watching the files individually. If they said "same time" most likely they just need to assure the date/time stamps on all the feeds line up.
If you really want to do it though, you can dump them all into a post production program like Adobe Premier or something then render it all together for them. However... 1. that is a little to much work, let the police do what they want and how they want. 2. Should this end up in court and you edited the clips or did some type of post production/export it could make help the defense question the evidence.
Best thing, just export all the requested footage. Same time/date range down to the second for each file/camera and just give it to the authorities that way.