I have a custom Entity - "Building"

That entity has a child entity called "BuildingAddons"

Child was created using the methods outlined here
https://community.sagecrm.com/partner_community/b/hints_tips_and_tricks/archive/2010/06/08/how-to-create-a-secondary-entity-for-a-new-custom-primary-entity.aspx#pi4178=2

Except I'm not using ASP pages I'm using the .NET API.

The child entity has a list page that is displayed on a tab of the parent entity.

Everything works. I can view add to the list of child objects, edit them, delete them, etc.

HOWEVER, when I navigate back to the summary page of the parent entity. IT LOSES THE ID OF THE PARENT ENTITY! So the parent summary page is now a blank data page.

If I look in the URL the Key58 argument is still set to the correct id. However, bldg_buildingid is blank so it reads "bldg_buldingid=&morequerystringstuffhere"

Without that being set the page will not pull in data.

Anyone have experience with this and have any ideas?