Oh the poor thing i always hated those stupid head lice treatments as a kid.

I don't have much experience with my DD as she is only 10mths but she loves her baths and showers, is there any way that maybe DD1 can help you with washing DD2 and show her there is nothing to be scared of, maybe get her to tip the water over her own head?

Maybe make it a bit of a novelty to take a doll in the bath and she can wash her hair while you do hers.

Maybe if she is scared of getting something in her eyes maybe a pair of goggles would help, she can play around in the bath, see under water and then you can wash her hair and she knows nothing is going in?

As i said i don't have much experience but i hope she gets used to it again soon for you, it's always hard when they do something that scares them from doing it again.

Miss A is learning to crawl and stand and keeps smacking her head, takes her a bit to get back to it...

Good luck with it all.