My headcanon is that Dunkaerion lived happily with their 8+ kids for 23 years. But one day when the whole family were having dinner at Summerhall with Maekar and the other Maekarlings, Aerion’s cup was poisoned with wildfire and he died right then and there, in front of his whole family.
The whole family is traumatized and in grief. Maekar has his trusted guards to find out who did this, but they find nothing. One of Aerion’s children suspects that it could have been a maester, and shares this information with the family, most not believing it initially, but they would all slowly end up only requesting the help from trusted maesters (like those that delivered the children or have been with the family for generations), when they needed one.
Then the rumor of him drinking wildfire because he thought he would turn into a dragon, is spread out very quickly, to the point that the family can’t even dispute them.
Then the Summerhall fire happens years later, and Dunk and half of his kids die in it along with Egg. The remaining kids leave, never to be heard of again and then one of them marries into House Tarth and then eventually Brienne is born.
The End.