run on a single writeback index?

[hashtag-24]

So, I work with an "elasticsearch-as-a-service" provider who requires me to manually create the indices prior to mapping and using them.
I have multiple different environment monitored, and therefore 4x as many indices to create (because some rules can have the same name between different envs)
Can anyone think of a way to use a single index for all the types of document ?
Is there any major blocker that I am not seeing ?
OR, is there any easy way to add a term to every written and searched document so that I could have 4 indices and documents in them identified by an "environment" term ?
Any help appreciated !