Simply put, you'll need to choose one continuity or the other -- that is, either apply for new 52!Damian or pre-reboot!Damian -- and stick to the chosen continuity exclusively. If you find that there are gaps in your chosen continuity that may call for headcanon, then you may draw material from the other continuity as long as it doesn't contradict anything in your chosen continuity. Such material must be italicized as per the headcanon protocol in the application. It would also be a good idea to label it as originating from a different continuity (versus wholesale headcanon).
As for characters whose back stories are changed, we'd ask the applicant to choose one story and stick with it exclusively.
no subject
Simply put, you'll need to choose one continuity or the other -- that is, either apply for new 52!Damian or pre-reboot!Damian -- and stick to the chosen continuity exclusively. If you find that there are gaps in your chosen continuity that may call for headcanon, then you may draw material from the other continuity as long as it doesn't contradict anything in your chosen continuity. Such material must be italicized as per the headcanon protocol in the application. It would also be a good idea to label it as originating from a different continuity (versus wholesale headcanon).
As for characters whose back stories are changed, we'd ask the applicant to choose one story and stick with it exclusively.