How to send job to ALL my slaves?

Hi everyone,
First post here and pretty new to Blender too !
I’m creating a 360 video animated on blender, and i’m trying to use network render to render faster, at the moment i have 2 computers ready. When I’m using the first one as a master and client and the second one as a slave, everything is working perfectly. But when I try to use the first computer also as a slave ( so indeed I have 2 slaves now), the job is only being sent to one of the 2 slaves (the one on the top of the slaves list). How can I manage to have my 2 slaves working ?
Thanks a lot