Hello Francessco,
it is not very clear for me what you intent to achive. Do you want to display a separate component? If yes, you can show a GUI Component independently from the both Dialog components involved in the transition. If you want both Dialog components showing the same contents, you can design them accordingly dupplicating the shown contents. If the separate component should perform an animation during the Dialogs are in transition, implement the component as Dialog and present it simultanously with the transition. See the section Perform several Dialog transitions simultaneously.
Best regards
Paul Banach