https://glowfic.com/posts/6263 Merrin has shown many signs that she is not drawn from the same distribution as the rest of dath ilan. Maybe she Isekai'd to DI, she's probably not actually a Sparashki, probably DI doesn't have soul mechanics that imprint the author's personality on the character, possibly authors get to play whichever dath ilani is closest to their own personality and therefore tend to get outliers.

You wouldn't expect Merrin's mother to also get through life unnoticed if she was as unusual as Merrin. This market resolves YES if by the story's completion, the story or Word of God confirms that Irris is not Merrin's biological mother. The close date is therefore subject to change.