I figured out how to do this with a Reference Qualifier on the dependent variable. For example, we have a requirement to make a child catalog variable "Sub Industry" dependent on the parent variable "Industry" on a catalog form. To accomplish this, I also wanted to have the child variable setup as a reference to a custom table as the values were an extensive list of Sub Industries. After I set up the child variable as a type of reference, I used a javascript in the 'Reference qual' field. The javascript used set the parent column label to equal the parent variable and looked something like this: javascript:'u_industry_parent='+current.variables.var_industry. I was having trouble when the child variable would be selected and figured out that I needed to make the child column on the custom table set with a Display value equal to yes. Prior to this, the value returning was the some other value on the table and it wasn't what I was looking for. I hope this information helps. I referred to a few articles on the community but couldn't find one that tied it all together.
