Multi-targer debugging for a single remote

[kotborealis]

I'm using this extension to remotely debug multiple processes on the another machine via some kind of a gdbserver.
The problem is that multiple processes (inferiors, in terms of gdb) show up as threads in the UI:

There's two processes, but they are not grouped in any way.

I'm aware that there's an option to start multi-target debugging, which displays processes nicely:

However, I'm not sure that this is the solution - I actually have a single target with multiple processes (inferiors), and the gdbserver in question does not support multiple connections.

Is there a way to trigger multi-target mode using only a single target and multiple inferiors?