Filtered Look-up for Custom Action Forms ability to get the lookup values from another input field

Please take a look at the example on the Clarizen Success website: https://success.clarizen.com/hc/en-us/articles/360025841193-Filtered-Lookups-for-Custom-Action-Forms?search=Filtered+Look-up+for+Custom+Action+Forms where the Parent Project is referenced and the advanced filters are leveraged. I would like to be able to get the customer object in this advanced setting.

For future reference, the feature request ID is CR-678558.