Take a look at the Wiki article re linking zones:
https://wiki.jriver.com/index.php/ZoneLinkAlthough JRemote2 on Android works fine for me with MC - it is a highly functional player/controller -
MC does not display it as a zone in my system. Perhaps someone more knowledgeable than me can comment: is there a JRemote2 firewall setting needed to make the phone appear as a DLNA zone via JRemote2, or some MC setting to make it a visible zone, or is this just another unresolved issue? Same story for Android players MO 4Media, JRiver Panel, and Gizmo.
However, when I run the BubbleUPnP for DLNA/Chromecast app on Android, the PC MC Server sees BubbleUPnP as a DLNA zone and can play to it like any other zone.
I linked BubbleUPnP (phone) with another audio zone on the PC MC server. Setting BubbleUPnP to
Renderers > Local Renderer, the MC server plays audio to both phone and the other zone simultaneously. Now when JRemote2 on Android plays to the zone, both phone (rendering to "This Device" in JRemote2) and other zone also play simultaneously under control of JRemote2! I am not set up to test video zones, but the audio works as you desire, so this scheme shows promise.
Linking these zones is not something I normally do, so I can't vouch for reliability. However the Android BubbleUPnP for DLNA/Chromecast app itself has been a very reliable player for me in the past and it is actively maintained. You can download a free limited version with ads from:
https://play.google.com/store/apps/details?id=com.bubblesoft.android.bubbleupnp&hl=en_US&gl=USI tested with the paid license version ($4.99):
https://play.google.com/store/apps/details?id=com.bubblesoft.android.bubbleupnp.unlocker&hl=en_US&gl=USNote: For this test, BubbleUPnPServer.exe (=BubbleUPnP Server, a completely separate PC program and service which is different from the Android app) was running in the background on the PC server. It makes my Chromecast audio devices visible as DLNA zones to MC. I would not expect that to be necessary in your case. I further confirmed that after shutting down the PC BubbeUPnP Server process, the phone remains a playable MC zone, while the Chromecast devices disappear as expected.
Another possibility: The Android player app MO 4Media allows you to link/unlink MC zones from within the app and has some video control capability (I use audio only). However it does not show the phone itself ("This Device") as linkable, so I don't think it will solve your case, and it does not appear to allow time offset adjustments. Otherwise this is a very nice, well-supported player (with annual subscription). You might submit an MO 4Media feature request if you are interested in pursuing it.
https://yabb.jriver.com/interact/index.php/topic,114964.0.htmlStill another possibility for running an Android server might be JRiver for Android, but unfortunately it's a $10 app without a free trial. I have no experience with it.
https://yabb.jriver.com/interact/index.php/topic,135113.0.htmlLast Updated: 2/10/2023MC 30.0.59 on Win 10 Pro 64-bit