how to do a all camera on one file recording with swann fourchannel h.264?

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Hello everyone,
English is my second language , I hope i posted in the right section.

I have a a swann advanced series four channel H.264 digital video recorder. under the apparel it is written swdvr 42550Hand under dvr4 2550 It has 15 years old but still works . swann do not answer the phone nor reply to email so i come to the community.

I have 2 cameras plugged in.
I can do recordings and watch them after but the system creates 2 distinct files , one for each camera wich means it takes double the time to review...

I am pretty sure it is possible to watch a review with all camera used in a sort of split screen from one file.

I did not find how to tell the apparel how to do it.

Any of you would know how to have the apparel create one single video where all cameras are visible at the same time?

thanks