The problem with Laurie taking them over, would be the same as Laurie being undead or not if there is also option of them going with Astrid. If split those paths too much too early it can get to hard to work on them, even if easier to keep those two out of the story after that besides a mention or two and a few renders.
Also it would mean Laurie has to be undead in near future on both paths then and around soonish to have that option, since I suspect Astrid mess will conclude in Episode 4. Would make more sense if you gave them to Fabian or suchlike who promises to take good care of them or something similar or a mindwipe by C and let them go free.
Though last would mean you would have same option for Carmen.
It can be done but as a dev you should really ask yourself if those two chars are worth the extra trouble and time, now Laurie is different as one of the main girls and even that split already led to two episodes where an update was just for one route and group of fans while devs worked hard. It is their choice though.