They should’ve treated her better aswell
Yeah the kids should've behave better sooner
True. But you really can't blame them. They didn't know why Shuli was brought into the household. They don't know anything. All they know was that some girl, close their age, replaced their mom. If Johannes explained even a miniscule part of his intentions, maybe they would have realized earlier what Shuli's purpose was. All they needed was guidance. But Shuli already had her hands full with managing everything. You can see the changes in her second life where she learned how to handle most affairs and made time for them.
Everytime they talk of sweet things they'd do in the future for Shuli, it just breaks me little by little knowing that it won't come true and theyd be faced with the reality of their mom's horiffic death. Now, theyre regretting so many things. This is pure torture.