Hey hun! Congrats on your pg!! Sorry I meant to reply this morning but got distracted with my cyclone DS, lol. Basically they replace the blankets yes, but you don't swaddle/wrap them up at the same time. My DS used to absolutely hate being wrapped up (would try and get his upper body out whenever he could especially his arms) so I only wrapped/swaddled him for 3 months and then I put him in the sleeping bags. You can get the bags from 0-6 months. If I was putting DS in the sleeping bag, I would dress him in his all in one bonds wondersuit with a singlet underneath. In winter if it got really cold I would throw a blanket on top of the bag as well, but then again he was sleeping in our bedroom in his cradle and the temp was quite cold at around 17 degrees. Then he moved into his own room and I kept the temp at a comfortable 21-22 degrees. I still put the blanket on top of the sleeping bag and all of a sudden I was over cooking him! I also used to use the thick winter bonds sleeping bag and with a wondersuit underneath, the room temp at a comfortable 21-22 degrees, and a blanket over the bag I was really over cooking my lil man. I am now a great big fan of the original grobag! I've recently bought the 1.0 tog which is fantastic for use all through the year (you can dress the bub light during the warmer months and dress them warmer under the bag in cooler months), so I only have a thin pair of pj under the bag and he sleeps so much better. The room temp is still comfortable 22 degrees, and this particular bag is good for room temps 20-24 degrees. The other bag which is 0.5 tog is for temps from 24-27 I think and the winter one is from 16-20 I think. Hope that makes sense!