Set rtabmap's initial position from the launch file?

edit

Hello,

I am looking for a way to set the initial pose of my robot from the launch file within rtabmap. I see that it can be done by sending the pose to the rtabmap/initialpose channel, but since I am running a simulation with many robots, doing this manually every time I launch the simulation (probably 100+ times a day, depending on what I am working on) for each of my robots (3-5, again depending) very quickly becomes cumbersome. I would like to be able to send this message (or set the variable, or something like that) from my main launch file, but I'm not sure how to do that. Alternatively, if I were able to set it from the rtabmap launch file I could set up separate ones of those for each robot that my main can call, but I would prefer to be able to do it from the main one. Can anyone help?

Thanks