Challenge #33: The Coffeehouse Family Reunion
Maggie has arranged a fun family reunion to be held at the Coffeehouse, in a private back room, small but comfortable. "Who's coming the the reunion?," asked Charles. With a crafty smile, Maggie replied: "One grandfather, one grandmother, two fathers, two mothers, four children, three grandchildren, one brother, two sisters, two sons, two daughters, one father-in-law, one mother-in-law, and one daughter-in-law. But don't worry about the small space in the back room, for not as many people will attend as it sounds. By the way, Charles, how many people will there be, and who will they be?"
Puzzled indeed, Charles hesitates, and asks you, his patrons, for some help. Provide you reasoned answer below, as you help out our poor, baffled Charles!
Describe who is coming, and how many there will be.