How to add a familly to an event

I was wonder if somebody could tell me how I would add a familly to a specific event chain. in ruler desinger you can have the customiser house trait and if you use that and advance the game 1 day you are presented with the event customizer_house.1 where you can choose "my familly still exists" or "my familly is extinct" well I've noticed that if you are playing say in the conquest time period you can choose a couple of houses that are not actually founded yet, for example house blackfyre, house slynt, blackwater, etc etc. well upon picking house blackfyre you are treated as the first member of that familly, yet you have no relation to the Targs nor the bloodline leading to Daemon, as he isnt alive yet. ergo you have basicily become your own High Valyrian familly not tied to the targs. and that got me thinking about it, could you add houses to this event chain? specifically I would like to add either House Truedrake or Fyreblood to this event, two of the cadet Dynasties of the targaryans, as then its a little way to overcome being related to the targs and constantly getting news about their claims and what naught, while also playing as a psudo custom dynasty. what would I need to do to add those famillies to that event chain?

EDIT: so ive managed to add house Fyreblood to the event however i am having this issue where when I select that house, 1. in the event it still says house Darklyn, and 2. it spawns characters that havnt been born yet as the parents and grandparents of my character. as in Donnel Darklyn from 8300 is adopting me even though the year is 7998 in war of conquest bookmark so im not sure ive done it right.