Question

I think the title says it all but ....

Problem is

1. If you create a subcase where the Parent has custom field values set, those values are not auto populated in the subcase.
2. If the Parent custom fields are a dropdown list then the first value in the list is selected in the subcase type

Solution Ensure all Parent case field values persist on Subcase creation

Answer 1

This might fit your expectation of how FogBugz should work, but there are plenty of people who would be surprised by this behavior. We try not to do things automatically that surprise the user.

If you wanted to do this via a plug-in, it would be trivially easy to do.