This, in common with all congratulatory letters, should be replied to
at once, and, wherever any missive is written in the third person, the
reply must follow the same fashion. An appropriate answer for the
above form would be:
Mr. and Mrs. Fielding unite in sending thanks to Mr. and
Mrs. Stuart for kindly praise awarded their son Harold on
the late important event in his life, and also for the
exquisite flowers they sent to grace the occasion.