Secret Santa is a Christmas tradition based around anonymous gift giving. It normally takes place among a large group of people especially a group who know each other like an office or school classl. Each member of the group is randomly assigned another for whom they will purchase a gift. There is usually a limit on the cost of the gift and gift suggestions may accompany the names. Gifts are collected and distributed without the identity of the giver being revealed, although in some variations hints are dropped.
A Secret Santa program for needy families can be set up in various ways. Consider how the program runs in an office or school and adapt this so that individuals give to the needy instead of each other. While you might want to also have the needy giving among themselves, or giving something smaller back to the more wealthy, it is a good idea to start with the goal of the wealthy giving to the needy.
The first consideration should be the needy group and just who the program wants to help. Ask questions like how will the group be identified? Will there be strict criteria or could anyone join it? Are they selected by others (like a church pastor) or do they self-nominate in the local drop-in centre? Are they local families in need or even poor people from overseas?
Secondly you will need to consider whether the needy group of people are merely recipients of charity or will themselves be involved in giving. If all participants will be required to give then organization will be easier, although you might want to consider setting different maximum amounts of gifts for wealthy and needy families, and will have to prepare for families who do not deliver on their gift because of some last minute crisis.
However, it is likely that needy families will be recipients only and having found the needy group the task is then to match them to wealthier willing givers. Gain expressions of interest from various wealthier groups who might like to be involved in giving - churches and religious organizations, schools and offices, successful businesses and so on.
Finding willing donors might be hard especially when the program is run as a charity from wealthy to needy. Donors might also want recognition in their local community for taking part or some other incentive that recognizes them, so consider whether and how they might be acknowledged without giving away individual identities to the recipients.
Thirdly, once givers and recipients have been found and confirmed then maximum gift amounts set it is time to match the Santas with those to whom they will give. You can randomly choose names from a hat, get the giver to choose a number that corresponds to a recipient, or have some methodical way of matching that will nevertheless make sure that the recipient will not be able to guess the giver. To prevent the problem of unwanted gifts get the recipients to nominate a few ideas along with their name. A timeframe should be set and a deadline for the gift.
Finally once gifts have been purchased or made they need to be distributed. It is often a nice idea to collect the gifts, clearly label them, hold them in a communal room and gather everyone together for distribution. If this cannot be done very easily then they can be delivered by a third party to the respective families. You might want to consider some backup gifts in the event that a donor doesn't turn up.
There are even on-line Secret Santa organizers that might be able to help with various aspects of setting up the program. Or modify the giving idea so that wealthy individuals donate money that is used to purchase food or toys or clothes according to need among particular families. However, it is probably not a good idea to simply stand on the street and hand out $100 bills as some have done since the gift maybe mis-used.