Is it possible to switch merlin version based on project?

I have multiple versions of ocaml (4.06.0, 4.02.3+buckle-master) kept track with `opam switch` at the same time.
But merlin would complain about wrong ocaml version in different projects.

Is it possible to use merlin version based on configs in the project (like a magic line in `.merlin`)?

```
# merlin: /path/to/merlin
```

or at least let me switch merlin path via file extension.