Controlling two "fans" for cooling

Basic Information:

Printer Model:
MCU / Printerboard:

Fill out above information and in all cases attach your klippy.log file. Pasting your printer.cfg is not needed
Be sure to check our Knowledge Base and in particular this and this post

Describe your issue:

Is there a way to control two print cooling motors such that one delivers air for lower flow rates but the other is used in conjunction with the first for higher flow rates?

Further details:
My printer has two diaphragm pumps feeding cooling air to a ring of jets around the printer nozzle - somewhat similar to a “Berd Ring”. The pumps are BLDC units and are only usable over about 30% to 100% flow. In order to get a decent range of cooling airflow I need to be able to go from one pump off and the other at 30% flow to both fully on.
I would think that this can be done with a macro that takes M106 Gcode, and possibly other fan control inputs, and splits it into 1 on/off output and 1 PWM output. So far I haven’t found a clue how to do it.
Detail questions are:
Can it be done in a macro?
Any recommendations on what literature to look at and what commands to look for?
My apologies for what is probably a simple question, but I am much better with assemblers than high-level languages - even Python makes me appreciate what dyslexia must be like.