Just Giving would be a good way for those who wish to donate in that way, as it automatically sorts the tax issue, and the latter is useful to the charity conerned, as it is effectivelyt "free" money. To achieve the gift aid element for any other way (i.e. people who want to make donations via cash, cheque paypal etc), then the total amount would need to be donated to the charity by an individual not by an organisation (but that is easy to manage, as it could be made by an individual who happens to be part of that organisation).
The key factors will be to provide options for donating that are easy to use and keeping the process simple.
The disbursement of donations should be as it is proposed, with a total amount raised split equally between the chosen charities, rather than left to individual choice. The latter would make it far more difficult to administer, and it would be potentially divisive were one charity to receive more than the others.
However, to meet Werner's needs now, we are running out of time - I suggest that it is left as it is now and the gift aid, payment options etc are addressed as part of the fundraising committee's early work to establish simple, acceptable processes for moving money around!
MG Mark
