Thats an interesting pitch. Those stories all make sense in isolation, but I feel like they wouldn't really fit with the game overall. Firstly, I think Selune instigating the whole thing would make her entirely unsympathetic and really ruin Shadowheart's story if it continued unchanged. Even ignoring the shadow curse that results from Isobel's death, Swlune is meant to be a good goddess and having her do something that intensely calous ruins that idea entirely. Shar doing something to make Halsin kill Isobel is better in tHalsin that respect, but in both cases it feels cheap honestly. Halsin has no agency, he was just there at the wrong time.