Hi @nipun,
We have forked and modified the Core Apps module so that it allows this, please see this thread: ‘How to use the Address Hierarchy Module with the Reference Application’.
We are meant to ‘request a pull’ 
on the OpenMRS repo for Core Apps and submit this once and for all. We just never really had the time but I will try to do so soon since my schedule is a bit lighter these days.
You may want to clone our forked master and give it a try. This is based on Core Apps v1.8, so the one for Ref App distro 2.3.
Any feedback on it would be welcome, we have only really used on a specific implementation.