I've found that, if I tell my DD to buy presents from me for the children it doesn't register with them that it is, in fact, from their granny. Better to hand the gift to the child even if it isn't actually on their birthday. I realised this when I gave my daughter some money to buy my grandson something when he went to Harry Potter World in lieu of an easter egg [as he had far too many easter eggs] and he said to me ages afterwards 'granny, why didn't you give me an easter egg
]'.It isn't that I desperately want them to know I've bought something but hate that they think I haven't bought anything.