Dimmer switch on fan/light combo
A &quot;regular&quot; dimmer, when used on a fan, will slow the fan to whatever setting is selected. This is awesome except for the fact that most settings will set up a very unpleasant harmonic thrumming sound. That's why a &quot;fan speed controller&quot; will have 3 distinct settings on it that match precisely with the 3 distinct settings you get by pulling the fan control chain on the fan itself.
You can do this, but you probably won't be happy with the results.
Instead, what you'll probably need to do is find a remote control dimmer that can be installed in the light housing and will control the dimming from the remote. You would want to find a system where either

the remote/receivers are programmable/pairable, or
there's one remote and 3 receivers, or
any remote will control any receiver

You would install the receivers in each fan, then use the one remote to control them all. You'd still have master control by flipping the switch on the wall to turn them all off/on (to the last brightness setting selected by the remote, assuming it has a &quot;memory&quot; function).