Well just stop feeling cross and a bit thick Grantasticpasta. Our children don't expect us to be up to date, I know mine struggle to keep up with the changing advice. One of the younger grandchildren is 20 months, his cousin 12 months. the advice on all kinds of things changed a lot in the few months between them being tiny babies.
We're grandparents, so we do our best to follow our children's expectations about the way we follow their routines and how we feed their children when were baby sitting/child minding/stepping in to hold the fort. I feel relieved that my grandchildren's parents all appreciate anything and everything we do for them. We aren't left with lists of things they can/can't eat or do, as I know some grandparents are.
I'm a bit handy with a biscuit, whereas my own children remember me being very strict about biscuits/cakes and sweets were reserved for Friday evenings only.