We have my partners funeral early November and requested donations to the community support group I chair and for which my partner was the sectary. It was done through Much Loved plus a collection box at the funeral itself. The Much Loved organisation pays out after 4 weeks, to make sure all the donations are in, I received a list of the donors and the amount donated plus their email in advance of payment and have written to every one of them to thank them individually. This is the norm for that particular giving platform. My neighbour died in December and they too donated to our Community Group, I have already received the list of donors so I can thank them but the money is as yet not paid out. How much to donate is a personal choice, but we did not have any donations below £20. As already mentioned funeral flowers even a spray are in excess of £ 50, but even sending flowers by Interflora or the like is now in excess of £ 35 and often more. Personally I would donate as much as you can possibly afford, it is your sister you are supporting, so turn it around and think how much you would have liked her to donate if it had been your husband's funeral. You have a good relationship now, although you do not see each other, keep it like that, as she will need you more than ever now.