I don't know about self-soothing? When my babies are upset, they want mom. They usually want to nurse and that will bring a smile to their faces. They will suck their fingers sometimes. They love to be held and carried so I usually end up wearing one and carrying the other or taking turns, and spend a lot of time on the floor or couch holding them. But they sleep on their own. They love to be swaddled and go down awake. Sleep is not a scary thing. They have slept 9-10hours for weeks. They don't need to nurse all night and are 50% for height and weight. But I would nurse them if they awoken. They just stopped needing to. There is something to be said for consolidated sleep and they nap 3 times a day too. In the crib. Without tears. That being said, maybe it makes a difference that there are two of them? Although my son slept through the night (10 hours) when he was around this age. I feed them often through the day. I just knew right from the beginning I did not want to make them unable to go to sleep on their own. So when they were tired, I wrapped them and put them in the crib. That made the crib a strong association with sleep and not having to nurse or need motion. I am with them all day, at night they need sleep, but they know that if they cry, we are THERE! We have a ritual at night and a shortened one for naps, pulling the shades, lots of kisses, sleep sheep, mobile if they are pretty awake, if they are really drowsy I don't use it, and definitely swaddling. Maybe not self-soothing, but we have power to influence shaping of sleep habits.