Letter of administration

With Letters of Administration, the administrator can access and manage the deceased's assets, including financial accounts and property, to settle debts and distribute the estate according to the law. 

The administrator cannot claim the property 

Yes. The administrator can manage the deceased's assets and liabilities after obtaining an order from the court and distributing the remaining assets as per law.

Very well analysed, opined and advised by learned senior experts, which I agree  to the extend of role / authority of Administrator appointed by the Court.

However, since D is stated to have been expired before testator of the subject will,  accordingly she (D) will not be entitled to the properties bequeathed in her favour as the will shall be applicable only after death of the Testator.

Since the Will was executed in favour of his parents (say Person B and Person C) and an younger sister (say  Person D), all the three legatees are the owners having 1/3rd Share, I presume.

However Letter of Administration is granted to Person D. and she also holds 1/3rd Share in the property by virute of testementary succession.

So I will reckon,   Person  B, C and D are the absolute owners of the property having 1/3rd share each and  Person D is to maintain the assets of the Testator.

Correct me if  I am wrong.

And thank you all for your valuable inputs.

Nagesh

Your understanding is correct, the role of administrator is that he or she has the authority to manage and distribute the assets of a deceased person's estate, here D herself is one of the beneficiary, she will also be entitled to one third share. 

Thank you very much Mr.Kalaiselvan.

regards,

Nagesh

You are welcome for your appreciations, Mr. Nagesh