Zachary is 2 weeks old

Yesterday we took Zachary for his 2 week checkup. There is no concern about whether or not he is thriving. He is now weighing in at 9 lbs 4 oz, putting him in the 80%. His height puts him in the 100%. He is at the beginning of a nasty case of baby acne. We were hoping it was almost done, but Dr. Collins said another 6 weeks. Our biggest issue continues to be Zachary's refusal to sleep on his back! Randy and I are not getting ANY sleep because of this! We were honest and shared with Dr. Collins that we let him sleep in his car seat. She said that is the worst thing we can do, especially developmentally. She indicated this could cause torticollis... we have been down that road with Q and don't want to again. We vowed to win this power struggle. We didn't make it one night. At 2:30 in the morning when we were both awake STILL, and desperately needed just a few hours, we caved and put him in the car seat. He went right to sleep for almost 3 hours. If anyone has any suggestions, or tips, we are so in need! Quintin is handling the adjustment like any 2 year old (with sensory issues.) Because Randy has been home it has been easier to give each of the boys one on one time but that is all about to change on Monday. I seriously have no clue how to get Q to bed with Zachary crying in my arms. Again, suggestions appreciated:-)