You can do this by using your field X as the related record for a self-relationship. Go to the settings for table ABC, and create a new relationship where ABC is both the parent table and the child table. Quick Base will say, "Gee, this is unusual. Are you sure?" Say yes! Be careful that for the related record field on the child side of the relationship you do *not* accept the default (which creates a new field). Instead, use the dropdown to select your existing field X. If you don't see X on the list of fields from which you can choose, you will have to abort the process, change the type of X to numeric, and start over. Then on X, check the box to display it as a link to the related (parent) record.