This may be a stupid question to ask, but what happens to your country if your heir is of another dynasty? My queen of Denmark is a Ylving and her eldest son and heir is part of the Hohenzellors dynasty.
Either get elective succession and nominate a Ylving (not realistic at all for roleplay purposes), or you can continuously save as your ruler gets older and older; when she dies you reload as her give all your land except for one county to her son.
Save, reload as the son, and keep playing as another dynasty (this IS for roleplay purposes).
This may be a stupid question to ask, but what happens to your country if your heir is of another dynasty? My queen of Denmark is a Ylving and her eldest son and heir is part of the Hohenzellors dynasty.