How can I get the parent primary key when creating a child record using a custom repository? The Create method passes in the entity but no reference to the parent ID.

I can see the parent ID is used in the outer iframe URL for the return path but unfortunately can't get hold of that using UrlReferrer.OriginalString.

Any ideas how I can get round this?

** Additional info

An example scenario of what I'm trying to achieve:

There is a relationship between two tables. The first table is People that are owners of pets, and when you click on one node in Owner it displays all the Pets that one Owner has in a ListView on the Owner editor. For the Pets I'm using a custom repository so when I click 'Create' on the ListView Action I need to know what the Parent ID is, so in this scenario this is the Owner. The Create method passes in the entity but has no reference to the Parent ID.

Thanks.