Hello, I recently purchased a cot and mattress that is 120 x 60cm. It is hard to find fitted sheets of this size. Is it safe to have larger fitted sheets on the mattress?

It is important that all bedding, including sheets, is not loose or at risk of covering baby’s head &/or face.
The bottom sheet does not have to be fitted (altho this is always easier) as long as it does not become loose.

Is the cot new & does it meet Australian Standards?
Does the company you bought the cot from have any suggestion for the availability of fitted sheets for this size cot?