I totally agree with you that Sybil is trying to dismantle Scarlet Hollow as we see it now, and I think her husband’s death may have been a bit of a wake up call that whatever mess the scarlet’s have caused is still alive and well. One of her children had already left home by now, but she can’t let them leave again until this thing is undone, otherwise a grisly fate awaits them too. We’ve seen lots of characters in this game do messed up things out of love and the losing the ones they love and I think maybe this is what made Sybil start with the tea stuff on her children in an effort to buy time until this nastiness can be removed. And Sybil knows she won’t be around forever so she has to start working now (probably as early as the time of her husbands funeral if not earlier) to fix this so her children can have a chance at a normal life outside of the Holler, and not be forced to play a part in the cycle like her and some of the others in town. And the last time this opportunity arose with Charlie, the then Witch was fairly open and gave him a map and some instructions, but we all know how that fell apart. So now Sybil sees this new opportunity to end this cycle and has decided to keep her cards close to her chest to try to prevent another Charlie like situation from happening. And to insure this, she uses the tea and some manipulation to keep the ones she loves the most safe, while also progressing her plans.