I don't have enough rep to suggest the synonym.
I modified the tags.
- I replaced interspecies-diplomacy with communication for 2 of them.
- I replaced interspecies-diplomacy with communication and added diplomacy for 1 them.
- I replaced interspecies-diplomacy with sociology for 1 of them.
- I deleted the tag for 3 of them because it was not required.
interspecies-diplomacy Has fallen into oblivion.
I don't think they're synonyms, but I also don't think interspecies-diplomacy needs its own tag. inter-species maybe, then you could pair it with diplomacy when you're specifically talking about governments.
Google definition of diplomacy:
the profession, activity, or skill of managing international relations, typically by a country's representatives abroad.
I don't really think (for example) Culture shock… Alien Social Activities should count as a question about diplomacy, but it certainly has a lot to do with interspecies interactions.
I think we can just use diplomacy. I don't think we need a synonym; if somebody types "interspecies-diplomacy" he'll get a match on "diplomacy", and if he means some other interspecies concern (e.g. biology) he won't want that. So I'm not sure a synonym actually helps here.