I posted on another mums group about using a thin cover less duvet in my child’s cot bed (21 months) and also cot pillow. I got told it’s really unsafe as they can’t kick them off as easy/get tangled up. Trouble is I can’t use sleep sacks as the size for there age is too small and the next larger size is to big. So does anyone know if this is true is it really that unsafe ? What about it I tucked one side right under the mattress ?