Anonymity is difficult with a private foundation. A private foundation is required to list the names of the directors on its Form 990-PF tax information return.  Equally important, a private foundation, unlike a public charity, is required to list all of its donors for public view.  The foundation can ask grant recipients to keep the grant anonymous and not to list the foundation in its annual report. But the foundation has to list each of its grantees on its Form 990-PF, so someone who knows the foundation exists can find out that way.

If the family members really want anonymity, they should consider using a donor advised fund at a public charity, perhaps a community foundation.  Public charities are not required to list their donors for public view. (Schedule B listing donors for the Form 990 is for the IRS only and need not be disclosed to the public.)  Although public charities are required to list their grantees, even if they list the grantees on the basis of the funds from which they distribute the grants, the donor advised fund can have a name that has no relationship to the family.  (See Ready Reference Page: “Donor Advised Funds Still Compare Well with Private Foundations”)