The property parent_case_id will be available under the 'Parent Cases' section at the bottom of your export if you're exporting the child case type. It should be fine that the parent and child cases have different case types, the bigger thing is that you're exporting the child case type.
Hi @btalbot , thanks for your help. Is this only available when you are exporting case data rather than form data? I've noticed that the parent_case_id is only available in the "Export Case Data" option. Is this variable also available in the "Export Form Data" option? Thanks for your help!
Yes, linking parent/child data through exports is only possible when performing a case export. I may not be able to help with your specific scenario, but did figure I'd ask: could you describe the end result you're looking to accomplish? Are you hoping to link forms that updated the parent case with forms that updated the child case?
If so, I do not think there's a clean way to do so in the CommCare UI. However, you may be able to achieve something like that using the CommCare Data Export Tool; though you may still have to filter the data in order to get the exact linking you need. Best of luck.