Integrating one rails application into another


I have requirement where in I need to integrate one rails application
into another.

We have two dashboards developed in RoR. Now, we are thinking of
integrating one into another.
We r thinking of migrating one of the dashboard entirely into another
i.e. along with its configs, routes, plug-ins used (required plug-ins
could be easily installed) and the last and the most important thing
is the database.

Please let me know what would be the best approach for doing this
integration. If there are some tools for doings this, however the
possibility are not quiet good.

Any thoughts and suggestion will be appreciable.