Thanks for all your replies.. I just wrote a really long response then my laptop refreshed and I lost it. I was trying to answer questions:
I was hurt by the comment that PP hopes I'm not in charge when my father is no longer here. I am doing everything he has asked, to the best of my knowledge and ability. I will only ever carry out his wishes. I don't try to manipulate him or change what he asks for, ever.
I wouldn't ask him 'for all 4 grandchildren' as this I think could be coercive, and as others say, although potentially hurtful, I am just carrying out his wishes.
I manage all the finances with his direction. He doesn't know how to login online, or make payments etc. He tells me who to pay, gas, electric, etc, and I handle all the household admin. It takes a lot of time, and I do it willingly, with pleasure to make his life easier.
I am not trying to take control or make him do anything inappropriate or against his wishes.
I don't know what the PP infers that they hope I'm not in charge when he's no longer here, as I wouldn't do anything that he wouldn't ask for.
My girls have always received modest, and very well received, gifts, for Christmas, birthdays, 21st etc, (£20-£30) which is adequate really.
I am a single mum with less financial security than my sibling who is a high earning professional, as is his wife.
I think my Dad has forgotten that when he gifted my girls as children, a generous amount, he also gifted the same to my sibling to pay off a chunk of his mortgage. The gift to my girls has been discussed recently, and I think this prompted this gift, perhaps, and he has forgotten that the same was gifted to my sibling (who didn't have children yet).
I don't want to change my Dad's wishes etc, and I will of course carry it out. (quickly, so that I can delete the email from my inbox and move on!!), but I still find it hurtful and don't want to. As other PPs point out, there could be other things I don't know about and it just happens that I know about this one.
I know that his will leaves everything split 40/40/20 between myself and sibling, and my Dad's sibling.
No mention of any grandchildren in the will.
I will, of course, let it go. But I'm hurt, and as PP says, maybe this is understandable after a lifetime of favouritism.