Master Tax Preparer
Enrolled Agent with 20 Years Experience specializing Individual and Small Businesses
IRS will not allow charitable or tax deductible contributions for private individuals.
The organization must not be organized or operated for the benefit of private interests, and no part of a section 501(c)(3) organization's net earnings may inure to the benefit of any private shareholder or individual.
Since the sole purpose of this proposed foundation is for the benefit of one particular family rather than for public benefit, you would not be able to gain approval as a qualified organization, and therefore contributions made would not be deductible by the donors.
I know this was not the answer you were hoping for, but I hope it gives you some clarity on this subject.