The One Where Rachel's Sister Babysits

Plot:

Monica and Chandler solicit Joey to write a letter to the adoption agency on their behalf. Joey discovers the thesaurus. Rachel's sister Amy visits and moves in with Rachel and Joey. She babysits Emma and gets the little girl's ears pierced. On their first anniversary, Phoebe spoils Mike's plans to propose, so she proposes to him. That doesn't go well, but the two get engaged anyway.