Looking for experienced ones in PRTG

Hi guys!

I've already asked this question in /r/prtg but that place seems a little empty.

I'm starting with PRTG and I'm stuck with dependencies definition.

My PRTG server has 3 hops before reach the Internet. In that last hop, my corporate firewall, I've connected a few MPLS services with several remote offices in them. I'm currently checking Internet and remote offices reachability. Also devices health (PING, CPU, memory and a few interfaces traffic).

When I say I'm stuck I'm referring to the question "who is the parent of all my network?" What's the criteria for this? I do know how to setup this, but the parenting concept implies a chaining that I don't know where it ends.

Thanks a lot for the help!!