I assume between two instances of OBS? Or are you trying to set up a virtual monitor on one to feed OBS on the other?
I don't have an answer for the second case (the virtual monitor), but for the first one, there are several plugins for OBS to send things to another instance of OBS with the same plugin. One uses NDI, which is an industry standard, and the rest do their own thing.
This plugin adds simple audio/video input and output over IP using NDI® technology. Three integrations are currently available: - NDI Source: add NDI Sources into OBS like any traditional source - NDI Output: transmit the main program view over...
obsproject.com
An OBS Studio plugin for an open NDI-like replacement. Pretty simple, straight forward. No NDI compatibility in any form. Just as an alternative option for stream setups with multiple machines wanting to transmit some OBS Studio scenes to the...
obsproject.com
Beam Seeking help with translations, please go here if you want to help, thanks! Beam (technical project name "xObsBeam") is an OBS plugin to transmit video and audio feeds between OBS instances, raw, or with lossless or lossy compression. An...
obsproject.com
There might be more, but that's what I remembered right now to search for.