Updating a union type doesn't copy existing settings

[rhyswfbowles]

Hi,

I've noticed that when updating a UnionField to include new models, the existing settings for this union aren't added to the new models.

For example when adding a new model to the union, the apiOnly state is not applied to the new model, but continues to exist on the older models.

Existing

New

As you can see, the visibility on the New one does not include the API Only from the existing one.

[notrab]

@flexzuu any idea on this?