Air Flow meter selection for parallel running fans

Hi all
We have an application where two FD fans are in parallel and we want to measure the flow.

My idea is to use a pitot tube type flow meter but, my doubt is that is it a good selection as for the fans generally do not work together but if in any case they run both the fans, then as they are in parallel the pressure stays same but flow increases.

  1. Is my understanding of parallel operation of fans correct???
  2. If pitot tube is not a good idea then which is the instrument suitable for this application with minimal tapping without any full bore to be created in pipe as it is a running unit and the pipe do not have any tapping as of now we can get some tapping if we require. But we cannot cut the pipe and put an inline flow meter(full bore is not possible.)???

any suggestions asap is very helpfull