Not really, suggestions just get passed for whatever nation the original writer asks for. Look at the Mowag Trinity, a swedish joint project with the Swiss as the Swiss sent the chassis to Sweden where Bofors mounted the turret to the chassis and began testing, most of its images show it at Bofors main training ground.
As far as we know the Swiss are most likely a subtree for Germany yet the Trinity was passed as a Swedish vehicle, imo it should be a joint vehicle like the DF-105 as Bofors was the lead when it came to the vehicles creation but stuff like the KF41 fight against it, but counter to that the Trinity wasn’t chosen so its not entirely the same and again should go to both trees.
I just think we should leave sub trees for nations that need gaps filled, or even variety. The US, doesn’t need any of that, it doesn’t need gaps filled or variety (from other nations through sub trees), it just needs Gaijin to actually add things that are suggested.
Chile is thee best one for Israel and for what we seen with the BeNeLux gaijin could go with Chile, Argentina, Brazil and Columbia as one sub via the Region rule