Piano as transposing instrument or how to override the key

I have orchestrated original piano composition in E major to brass section. For brass instruments the composition has been transposed to Eb major. Could someone tell if there is a solution in Dorico to retain the original key for piano? Piano line is only for reference and not actually intended to be played. So far I have not found means to override the key or to transpose piano part.

I’d say you have to create an independent key signature for the piano (by way of modifying the entry with Alt, either with the mouse or as you enter Return in the popover) and transpose the music just for that staff.

Thanks for the quick and right answer!