Raelle is strongly encouraged to find a male witch to marry for dynastic purposes despite being an out lesbian, yet if it's possible for magic in this setting to allow a woman to have a daughter by three different fathers as with Abigail's mother, which is stated to be the average number of fathers for High Atlantic witches, then you'd think it would be possible for two women to have a child via magical Homosexual Reproduction as well. Scientists have already done that with female lab mice in our world.
The whole reproductive strategy pressure seems poorly thought-out. Soldiers who are only 18 or so are being simultaneously pressured to pick mates and to be shipped to the front lines of combat. These two things don't work well together. If there's a serious shortage of witches of good bloodlines, it would make sense to pressure all the dutiful soldiers to have a baby first before risking their lives, so that their legacies are assured, and education and training could be wrapped around the critical time period of bearing and nursing. If the desire is to put soldiers into combat first so that only the strong survive long enough to raise families later, then what's the purpose of trying to match them up with mates right now? None of the women we're seeing raised to take pride in their identities as fighters are going to be eager to stop and have a baby right now, and early failed marriages would seem to make it less appealing later. But then, perhaps that's exactly why they're having a problem keeping the witch population going.
It is also amazing that there does not seem to be any kind of societal pressure, campaign, anything, to encourage having more than one child, for the sake of maintaining their numbers. Of the three leads, none of them have any siblings. Abigail's mother has a sister but apparently only one, who also had only one daughter. Their peers of similar ages don't mention siblings either.
