Unfortunately we don't support path-based routing. 
I wanted this too for our own deployments and really tried to get it to work, but as far as I can see there's no good way to do it that doesn't require recompiling the front-end once the desired subpath is known.
The solution is to use subdomain routing instead. So instead of /instance_one/get_questions you'll have instance_one.example.com/get_questions. See further discussion here: Feature request: URL prefixing