@futr_vision - you are running the risk of over engineering your app for no reason and getting into errors.
As mentioned in the other post, creating a Variable from a Gallery selection, and then associating that variable to the Item property of an Edit Form control, or associating the Item property with "Gallery1.Selected", will return the same result (a record will be returned).
Based on this understanding, there is no need to populate the Default control with "Your Variable.'Your Field".
If you must use a Variable, ensure the Item property is set to your Variable, ensure the Default property for each control is "Parent.Default" and the Default Property for each DataCard should be 'ThisItem.'Your Field'.