Notifying Court of Protection of application for letters of administration by attorney under LPA

A male died intestate and his mother is the sole entitled person. She has lost capacity but did create and LPA appointing her other 2 children. I am assisting them in applying for letters of administration.

I am aware that it is necessary to notify the Court of Protection of the application but cannot find out whether there is a specific procedure (I tried to contact the court to check but needless to say havent had a response). Is it sufficient to write a letter to the Court setting out the circumstances?