Thanks for the chapter!
Knew those two were more than simple servants. As for marrying at 15 it's likely due to a low level of medicines, treatments and knowledge so mortality rates were higher thus prompting to marry and have children young. Although a large part of the mortality rate is likely due to fighting within families and other families to the death over little things. That and servants were considered disposable labor that could be used and abused as the family likes where even minor mistakes or receiving punishment to shift blame from a family member could result in being crippled or killed. As long as it was done within the family property quietly the town guards wouldn't care other than complaints over the corpse making a stink. That and when kicked out would usually be just the clothes they had on their back, no opportunity to gather their things, and a possibility of being black listed to avoid offending the family no matter how innocent the servant or how evil and corrupt the family is.
Btw, didn't get this at first but by MC giving her sister slippers made of a national treasure would really raise the value of the sister in people's eyes. Even though not a full set of clothes just the fact that she has something made out a national treasure is equivalent to her having a jewel with a really large and valuable stone.