Setting ShowInEditForm declarativ for a field in a content type

Hello,

I've a custom field definition. I want to set this field invisible in the EditForm of some content Types, it should stay visible in other content types.

So when defining the CT´s, I set the ShowInEditForm property to false for some content types. However deploying the content types, adding it to some lists for testing shows that my setting are ignored.

Then I tried to achieve this within an eventreceiver after deploying the content types. But CT.FieldLinks["Field"] has only a ShowInDisplayForm property.

Can I achieve my goal only on list level?