She has always given my niece and nephew a pound a day for an ice cream when they go on holiday. We've been on holiday 3 times since ds was born (this will be dd's first holiday) and no ice cream money. I wouldn't dream of asking why, but I suspect it's because we have more disposable income than my sister but it does make me sad as I think it's a lovely tradition and it seems unfair one set of grandchildren should be treated when the other set isn't.