Not a teacher
I'd write: The girl is playing with her baby sister that/who is lying in the cot.
[not a teacher]
FYI, that is not a cot in the picture, it is a crib*. (I do understand your assignment requires "cot".)
*I see now that this is an AmE distinction.
2 British : crib
Thanks everyone! I got it.![]()
If she were 'playing with her baby sister by the cot' they'd both be on the floor by the cot - quite possible, but a different picture.
b