Great suggestions above. You can use a dropper or an infant medicine syringe from the pharmacy to place a drop of green water or BBS in front of them conveniently.
I have a syringe that I'm using for the green water, I'm putting some in 4/5 times a day & they react straight away to it so they seem to know it's food.
The adults all seem to be displaying tonight, so might be more babies on the way soon!