Don’t forget, the Borderlands origins comic had an old siren who told Lilith about her powers, and died early on.
Asha also appeared and could control animals.
Both of those are dead if I’m not mistaken and we don’t know how siren powers transfer. They might pass along to the female in mind when one dies (Steele’s focus on the Vault and what it will give her while ignorant of possible death could mean the power would randomly jump)
Roosterteeth has that happen in RWBY where the season maiden powers pass along to thought, or randomly if no suitable candidate is thought of, unless partially siphoned.
Angel, knew she was going to die and may have thought of a new power carrier by the time she died, thus projecting her powers. She had the Hyperion surveillance network at her fingertips, she could easily have seen a remote suitable candidate to keep her powers from Jack.
Asha, we know very little of. She could have died via surprise and her powers go to a new carrier, or if she had someone in mind them.
Ultimately we know near to nothing of sirens and can’t do anything more than speculate with shots in the dark.
From the Wikipedia page on sirens. However the link the reference goes to has been removed so it’s not completely off the table. And comes as a surprise to me.