Automatically mount(link) the external partition in system datastore on node

Hello!

How can I automatically mount the external partition /srv/extsrg in /var/lib/one/datastores/ on a working (new created) node?
If the is known after the datastore(SYSTEM) is created on the frontend node.
The key point is automatically, without manually doing ln -s /srv/extsrg /var/lib/one/datastores/.