Joint custody laws in TN?

Does anyone know how joint custody in the state of TN goes with new born's? I'm expecting twins in September and the father and I would like joint custody. I would be the primary parent. He has joint custody of his other daughter and sees her every other weekend. I plan on breast feeding my babies for as long as possible. With there being 2 babies I see it being kind of hard to pump enough bottles for the both of them for an entire weekend. I just need the information. Thanks.