Yeah!! I am so glad you got some babies. Can't wait to see pics. Yours are about a week older than mine. It will be interesting to see how many hens vs. drakes that you got. Did he say what they were or did he know? Baby Muscovy drakes usually have bigger feet than the hens. With four to compare to each other, you may be able to tell. If they all look the same size feet, then you have all drakes or all hens. Otherwise, maybe you can tell.
Waiting for pics...