What is the main conflict in Thanksgiving by Janet Evanovich?

Megan Murphy is having a makeshift picnic in a park in Williamsburg when she encounters a large, fluffy, friendly rabbit—eating at the hem of her skirt. Patrick Hunter approaches, tells her it's his rabbit and teasingly fusses at her for feeding her skirt to the rabbit. She later sees the same rabbit and takes it back to Patrick, planning to scold him for his lax pet parenting skills. But before she has the chance to tell him what she thinks, a young woman named Tilly Coogan rushes in, hands Megan her young son, says she'll return in a couple of weeks, and rushes out again. Patrick immediately searches for members of Tilly's family but finds she has none listed on Tim's patient information. Meanwhile, Megan has rocked Tim to sleep and discovered that she enjoys mothering the little boy. Patrick says he'll have to hand the child over to child services, but Megan objects. They eventually come to an agreement to have Megan watch the little boy during the day on weekdays when she doesn't work as a visitor's aide for tourists. Megan, who doesn't call herself an "artist", makes teapots for sale in shops around the Christmas season. When Patrick realizes that she has this commitment, he offers to find another sitter, but Megan has by that time become committed to the little boy. She soon falls into a routine with him and notes that she, Patrick, and their families don't seem to consider the possibility that Tilly may return for Tim.