if I don't give my DD2 prunes at least every second day she gets horribly consitpated.
I just get a whole packet and blend them up into a paste with water and then every second day give her a couple of teaspoons with her oats in the morning.

If she is especially backed up then I give her a couple tablespoons on its own mixed with some water to make it not so thick.
She seems to love them which is good, poor thing doesn't know any better

Works a treat and she feels so much better for it.