I have a custom entity. This entity is related to several other entities. On the form for this entity I have the related items displayed in lists under a tab for each relation. The lists allow you to "Add an item" when in Edit mode. If I choose to add an item from here I get the create/edit form of the related item in a popup. This is great but I also want to pass default vals from the parent entity such as it's ID and name in order to establish it's relation instead of having to select these on the create form. Can this be done?

Let's take it further. The orginal entity is A. I select add an item for a related entity B and want A's relation set by default. Then from B's form I choose add an item for related entity C and want that item to have the same relation to A as well as the relation to B set by default.