Channeling the presumed generosity of others by directing them to donate to a particular charity may be well-intentioned but is certain to give offense to at least some of those you importune for donations. Gifts are purely voluntary tangible expressions of the affection others have for you and cannot be “tapped” as a resource, no matter how worthy the intended recipient.
Christmas wish lists are for children writing to Santa. Adults in your situation may say modestly in response to any voluntary inquiries they receive as to what they would like for Christmas, “I would very much like to support the work of [insert favorite charity].” If they receive gifts they do not need or cannot use, they must graciously thank the giver and then they may discreetly dispose of the gifts and give any proceeds from such disposal (e.g., garage sale, eBay, etc.) to their favorite charity.