Hi Anvika,
There is currently not a native functionality to convert an existing table into a connected table. Connected tables have to be designated as such when the table is very first created. If you feel this would be a beneficial feature in Quick Base, I would encourage you to submit feedback regarding this via our Feedback Platform - UserVoice - Which can most easily be accessed from the My Apps page in Quick Base by clicking on the orange Feedback tab or at
http://quickbase.uservoice.com. This forum is used by our development team to explore customer suggestions for enhancements / changes to the platform. Many of the items that have been suggested by customers have already been incorporated into Quick Base and I would encourage you to participate as well.
