Oligo.....I am a nanny in a full time nanny share.
As instructed by NANNYPAYE (whom both families use and I would HIGHLY recommend having a chat to),I have 2 contracts - one for each family. Details and content are EXACTLY the same apart from the hours worked. For one family, I am down as working 8 am till 1 pm Mon-Fri. For the other family, it is 1pm till 6pm Mon-Fri (even though I have both boys 8 till 6. This all come down to a very complicated minimum wage hoo haa that I can't quite explain here without an enormous ramble) 
They have split my salary right down the middle. That way, they are EACH responsible for their own tax returns and NI contributions.
Both families use the vouchers, so it's just been a case of getting those payments made at the same time as the 'bulk' of my salary which comes from the parents personal accounts (am I making any sense here??)
So to break it down.
FAMILY A - contract says 8am till 1pm
'voucher' money paid into my account at the end of the month along with the remainder of their half.
FAMILY B - contract says 1pm till 6pm
'voucher' money paid into my account in the middle of the month along with the remainder of their half.
I REALLY hope that this has made sense! I am not the best at explaining things 
It may appear complicated but I can assure you that it is not - if I can understand it then anyone can 
Hope to have helped rather than hindered!