Hi Ib15.
I don't think what you are looking for is really possible. After all, this is why Campaign has branding to begin with. In general, you should be setting up branding and then, based on the targeting in your workflows, create segmentation activities that split your recipients into different populations that then go to different deliveries based on branded templates.
Additionally, in general, it's a smart practice to keep whatever can be done beforehand, either in templates or the upstream targeting out of the delivery activity, to reduce the delivery size and complexity, which can lead to longer delivery preparation and send times.
Regards,
Craig