My 3yo DD recieved a lovely children's book instead of a party bag from a friend recently (a MNetter too).
It is a really lovely book, and the the whole thing is about co-sleeping, albeit in the end with 7 children!
It is: TheBiggestBedintheWorld by LindsayCamp*
Ben's dad wasn't getting much sleep. There were too many children in his bed. Not just Ben, but also his baby brother Billy. And then the twins, Beth and Bart, arrived. There was only one thing for it...Ben's dad fetched his tools, and set to work building the biggest bed in the world. At last he had enough room to sleep comfortably, even after the triplets, Briony, Bella and Boris were born. But, unfortunately for Ben's dad, he still had a problem. The biggest bed in the world was also the heaviest bed in the world and one night, in the middle of the night, it began to move...Lindsay Camp's hilarious tale will delight pre-school children, who will love the rhythmic, patterned language and the outrageous idea of a bed on the move with a whole family asleep on top of it. AGE 3-7
There is also one illustration clearly showing mummy breast feeding too.