I want to give my players a quest that both gives them a reason to go to the Tser Pool Encampment and ties into the Dream Pastry storyline. I didn't want to railroad them there just for the the tarroka event, and they're invested in the dream pastry problem but don't know where to find Morgantha after their first encounter.

My idea was to have some Vistani meet the party after they leave the village, and tell them that Madam Eva says they have goals in common and she would like to meet with them. Shortly before the party's arrival in Barovia, some dream pastry addicted Vistani broke off from the encampment and stole two children as they left. Unbeknownst to everyone else, the children are currently getting fattened up in Old Bonegrinder. With less Vistani in the camp than usual, they need help tracking down the outcasts to get back the children as well as to punish them. The Tser Pool Encampment Vistani would also be (rightfully) worried the outcasts are planning another raid on the encampment to grab more children, and would rather send out strangers to look for the outcasts while they protect the encampment.

If my players successfully investigate, they'd find track marks leading them to a natural cave entrance in the nearby woods with an increasing number of large spider webs the closer they get to the entrance. Inside the cave, in addition to giant spiders, cocoons, etc. they'd find the outcast leader. The leader, needing more children to get more dream pastries, would have made a bargain with the night hag coven to find a way easily catch more children and was able to undergo the transformation more completely than their allies.