Taxability of income from PRIVATE TRUST FUND , when the Trust is settled for specific needs

Dear Sir/Madam,

In case Parents of handicapped dependent wants to settle a private irrevocable discretionary trust , kindly guide/advise the tax on the income generated from TRUST Fund as per query stated hereunder.

a) In case of irrevocable discretionary trust , if the same settled for the well being , support and maintenance of the handicapped dependent , how the income tax on the income generated from the TRUST FUND will be assesed in case the TRUST is settled for the specific needs of well being , support and maintenance of the handicapped dependent. Whether the Trustees will be taxed for the income generated from TRUST FUND or the same would be taxed on beneficiary level or contemplated assessment of the same income both in the hands of the trustees and the beneficiaries,

b) Is it necessary to settle an irrevocable non-discretionary trust for the well being , support and maintenance of the handicapped dependent in order to avail the benefit of taxation by the Parents with handicapped dependent or it may be an irrevocable discretionary trust as well with provision of keeping Parents as Trustees in order to have better control and structure the deed and instrument accordingly in order to avail exception as per terms laid down in section 164(1). 

c) Whether it would not be legally permissible to convert the character of the discretionary trust to specific trust , if yes , then whether applicable section for tax of discretionary trust would be 164(1) and  for allother cases it would be governed by section 161 and 161(A) ?

d) Whether Parents can continue availing exemption under section 80DD while filing ITR and also Trust can avail or claim deduction under chapter VI-A ?

Appreciate response from learned experts in order to clarify and understand the taxability of Private Trust created and settled for a specific needs as mentioned above.

Thanks and regards