The Manager shall in the prescribed manner determine the amount of the principal of all debts and liabilities not barred under section 10 justly due to the several creditors of the Nawab Bahadur and to persons holding mortgages, charges or liens on the property of the Nawab Bahadur, and shall determine in like manner the interest, if any, due at the date of such determination in respect of such debts and liabilities and may reduce the rates of interest charged as appears to him just and proper.