Yep, this is the place i found it, though including the line parent="master" inside the client-host object definition, ruins all the checks we wish to execute locally on the client itself (e.g. disk & memory).
It seems it is needed for checks like ping or ssh, that we want to be triggered from the master side.
Anyway, I will create the icinga2-master1 directory as you suggested for completeness and symmetry in config design.
So i guess i do not need to change anything else in my config?
I can share any .conf files you may wish to review.
I will try to visualize the concept as suggested