“special trust” means a trust created –

(a)     solely for the benefit of one or more persons who is or are persons with a disability as defined in section 6B(1) where such disability incapacitates such person or persons from earning sufficient income for their maintenance, or from managing their own financial affairs: Provided that-

(aa)   such trust shall be deemed not to be a special trust in respect of years of assessment ending on or after the date on which all such persons are deceased; and

(bb)   where such trust is created for the benefit of more than one person, all persons for whose benefit the trust is created must be relatives in relation to each other; or

(b)     by or in terms of the will of a deceased person, solely for the benefit of beneficiaries who are relatives in relation to that deceased person and who are alive on the date of death of that deceased person (including any beneficiary who has been conceived but not yet born on that date), where the youngest of those beneficiaries is on the last day of the year of assessment of that trust under the age of 18 years;