Hi there - I'm having some (sort of) success with introducing a blankie / comforter. My ds just went down for his nap holding a muslin square I'd been sleeping with for a couple of nights. But then I've been fretting that maybe he'll get it in his mouth / over his face etc etc (I've just checked him and so far OK). He's 5 months. Surely he could breathe through it / pull it out of his mouth? Reassurance please!