I'm not entirely certain there is a connection between Etta and the kin. Saga might be half dragon just because she is the spiritual reincarnation of April.
Magus mentions in one of the memories about how it makes him uncomfortable that Galath seems to only visit to see Saga. If Saga is reincarnated April, then I wonder if Galath is someone that knew April previously or at the very a least one of the kin coming to keep an eye on her. The obvious choice would be Cortez. However Queenie really reminded me of a red dragon, and Saga mentioned being taught by the madam. Alternatively Galath could be Brian Westhouse, which would leave me with the creeps too.
I definitely do agree though that Saga/April Ryan/ their various reincarnations are going to be tied to HoAW. After all Magnus said it would be the one place they could always find their way back to regardless of what happened.
Alternative crackpot theory: Magnus, Etta, Galath, and Madam could all be dragons. Maybe they are each one of the four dragons: Magnus as red, Etta as white, Galath as green, and Madam as blue. Magnus and Etta are just their generations version of the red and white, and upset that one is forced to live in Stark while the other is stuck in Arcadia, they build the HoAW. However since it is outside of time, creating it resulted in it always existing, and now all four of them and April/Saga might be tied to repeatedly return to HoAW over and over again with each life that they live, always reincarnating to continue the circle.