custom branding for different clients

Hi Phil, 

Welcome to Box Community and glad to help! 

As of this writing, this feature that you've asked about is a current limitation for custom branding however, it can be subject for a feature request.

Please feel free to upvote here to include your feedback and suggestion. Our product team reviews all submissions and will consider whether to include feedback in their product roadmap. 

Your feedback will be greatly appreciated, stay well!