Mallard Ducklings

Neighbor had a Wild Mallard duck who made a nest in her pond area. 5 ducklings hatched 2 weeks ago. She tried to get someone to catch them and take to local lake. They’ve now started to wonder around our garden. No issue for us except we have foxes in our area. 

Lost one night before, duck was screaming for 2 hours. There was 4 yesterday. Woke up to hear duck screaming again this morning and chased away fox but could only see fresh pigeon feathers across the garden. The duck flew back to neighbours garden. Now can only see 2 ducklings with mother.

Question. Do all ducklings follow the mother or will she take 2 at a time? I’d like to think she still got her 4 hidden away.