Mother and Son 5x6

Secretly doing some babysitting during the day, Maggie gives away what shes doing when Arthur sees she's knitting a baby booty, but when he discovers the baby, he thinks she's kidnapped it from the shop. A visit from Robert and Liz prompts them to check on the baby and a letter that Maggie received in the mail for Robert leads Arthur, and eventually Liz, to think the baby is Robert's. Will Arthur find out what Maggie is up to?