Hi!
Hope you are doing well today.
The answer is:
M. F. S. B. (Mother, Father, Sister and Brother).
Their single, " T. S. O. P. (The Sound Of Philadelphia) " hit #1 in 1974.
This was the theme for the T. V. dance show, " Soul Train ".
Have a beautiful and Blessed day.
S - M - I - L - E !!!
Take Care!
God Bless You!
Paul Carter Jr.