How to configure GdSceneSynchronizer in case of two connections?

[Malkverbena]

If I have two connections in the same scene, how should I configure GdSceneSynchronizer?
Would I have to have two singletons?

[AndreaCatania]

Yes, or a single singleton that under the hood instantiates two (or more) different GdSceneSynchronizer.
In such a case the API would look like:

NetSync.sync_layer[0].register_variable(...)

[Malkverbena]

I guess that multiplayer(property) of GdSceneSynchronizer also must be set, correct?

[AndreaCatania]

Yes, each GdSceneSynchronizer must have it's own (or shared) MultiplayerAPI set as usual.