Notice That They Were Only Going To Give Daella One When They Still Thought She Would Marry Vaegon - Tumblr Posts

the fact that both Viserra and Saera don't have a dragon, just like Gael. It is that they were no longer fit for the Targaryen house, they could not marry their brothers, so they simply were not worthy of it, because they were only fit to marry another house and obviously they were not going to allow them to have their dragon, only Dragon's blood it matters in women when it is useful for men.