force rootmac on bridge

quick question …

i have a bridge type setup in my environment.

almost all of my routers are merely bridges.

so for example my main router that does everything (hotspot and pppoe + provide internet) has ports 2-6 bridged.

then i have a 9 port rb2011 connected to the main router above via cable.
the rb2011 also has ALL ports bridged.

i am told to set the root mac on the main router to 00:00:00:00:00:01
that way it forces all bridges to return to the main router bridge for efficiency.

do i have to set 00:00:00:00:00:01 on all the units or just the main router?