I know I have introduced many new characters, mostly children of the original Hogwarts trio and those related. So here is a chart to help you keep them straight. I have written in the years to help you figure out how many years are b/t the children. Since Ginny graduated Hogwarts in 1999, I worked up from that point…so this takes place in the "future" but only in numbers. Some might appear, some might not, but I hope this helps you all the same.
Ginny and Draco's children
Marissa-Jan. 14, 2000 (Ravenclaw)
Devon-Feb. 20, 2001 ( R )
Derek-April 1, 2003 ( R )
Dixon-April 1, 2003 ( R )
Erin-April 1, 2003 ( R )
Harry and Hermione's children
Brian-May 15, 1999 (Gryffindor)
Laura-March 29, 2003 (G)
Taryn-March 29, 2003 (G)
Kirstin-March 29, 2003 (G)
Ron and Samantha's children
James-February 7, 2000 (Gryffindor)
Jeremy-October 12, 2002 (Gryffindor)
Charlie and Katharine children
Jillian-March 5, 1998 (Gryffindor)
Cassandra-March 5, 1998 (Gryffindor)
Bill and Fleur's children
Gabriel (Gabe)-November 2, 2000 (Gryffindor)
Fred and Maggie's children
Sean-February 1, 2002 (Gryffindor)
Arthur II-May 5, 2004 (Gryffindor)
George and Lavender's children
Molly-December 24, 2002 (Gryffindor)
Kenneth-January 30, 2005 (Gryffindor)
Percy and Penelope's children
Reginald-September 29, 1999 (Slytherin)
Neville and Luna's children
Cora-June 2, 2001 (Ravenclaw)
Anna-February 26, 2005 (Gryffindor)
Other characters mentioned: ( I may add some in later chapters, but as of chapter two these are the only ones I can think that might be mentioned)
Oliver Wood-son-born in 1997 (Gryffindor)
Pansy Parkinson-daughter-born in 2003 (Slytherin)