To begin with, sorry for my low level of English and thank you for your advice...
Ultimately it seems to work well and without doing anything special.
The click track fits on the auxiliary channel of the MR18, so I can route it however I want in each musician's monitoring buses.
As we see here there is no cue configured.
View attachment 18526
Here I just kept the overall volume and deactivated those of the cues.
View attachment 18527
We can clearly see the click activate the stereo auxiliary track of the MR18 that I routed in bus 1 which is that of the drummer.
View attachment 18528
I of course disabled the main stereo output of the auxiliary track to avoid hearing it when checking the recordings.
To be checked in real conditions next week during recording...