I would like to Dimension the family instances. What is the reference I should be provided while creating dimension.
I have tried with several approaches but the dimensions are not getting deleted when I delete the family instances. This means that, the dimensions are not getting attached to the family instances.
Please help.
Have you found a way to address this manually through the user interface? That is mostly the best place to start when tackling a Revit API task. If you can solve it through the UI, the chances are good it can also be automated. If no UI solution is found, automation is mostly impossible as well.
I would analyse the exact differences caused in the Revit database on the elements involved and their parameters by executing the manual modification. Once you have discovered exactly what is changed by the manual UI interaction, you can probably replicate the same changes programmatically through the API. Here is a more exhaustive description of how to address a Revit API programming task: