start again.
sit down and calmly tell them that we are going back to basics on hygiene.
make a little sign for the bathroom
- pee/pooh
- wipe
- flush
4 wash hands with soap
5 dry hands
Show it to them, and then say, you expect that every single time. As far as possible, every time you hear them go, go and wait outside the bathroom.
When they come out, ask them if they remembered the 5 steps? Check where you can (is loo flushed, is basin wet, has towel been used.
Give them praise when donw and send them back to start agian when not done.
As starting again will take longer, it will be to their advantage to do it first time.
Then meal times, when you clal them to eat, send them to wash hands first. This is good practice anyway. I remember my mum ALWAYS sending us to wash hands before dinner.
Inspect hands as they sit down. They should be properly clean, and wet and if necessary give them a sniff, if they don't smell of soap, send them back.
I have sympathy, I too realised the hand soap in the bathroom was not being used up and did a bit of shaming to rmeind them, but mine are older than yours.
As to shampoo, I think at 8 and 10, there needs to be some supervision eg, - ds it is shower time, please make sure you wahs your hair, and then checking afterwards it is clean as well as wet.
I regularly send all of mine back upstairs to do teeth as well.