Are the following provisions in a Will valid according to the Shariah?

Question

Are the following provisions in a Will valid according to the Shariah? "I hereby direct that any inheritance accruing to a minor child in terms hereof shall not be paid into the Guardians Fund but shall be held intrust by my said executors and administrators until the said minor attains the age of 25 (Twenty Five), in which event my said executors and administrators shall pay over to said minor his/her inheritance. 12. POWERS OF MY EXECUTORS AND ADMINISTRATORS For the purpose of winding-up my estate and for the benefit of my heirs and beneficiaries, I hereby confer inter alia, the following powers upon my executors and administrators:- 12.1 to sell, lease or alienate any assets of whatsoever nature whether movable or immovable, whether by public auction or by private treaty in their sole discretion for the benefit of the beneficiaries; 12.2 to make interim payments for the maintenance and support of any beneficiary "on account" until the winding-up of my estate is completed and the estate is properly distributed; 12.3 to continue any business carried on by me for the period as from the date of my death until the estate accounts are approved without objection and the estate is distributed to the entitled beneficiaries in accordance with the provisions hereof."