I've changed some dates and ages. James and Lily finished school in 1977 rather than 1978 and Lily was pregnant before she Graduated.

Bill- 29th November 1972

Charlie- 12th December 1974

Phoenix- 5th April 1975

Percy- 22nd August 1976

Fred and George- 1st April 1978

Rory- 20th November 1977

Isaac and Logan- 11th May 1978

Harry- 31st July 1980

Ron- 1st March 1980

Ginny- 11th August 1981

My Characters 

Aurora Nova Potter (Rory)- Older daughter of James and Lily Potter 

Evelyn Mia Potter (Evie) (James' Twin)

Isaac Fleamont Black and Logan Remus Black (Twins)- Twins of Sirius and Evie 

Phoenix Siri Black (Nix, Nixy)- Sirius's Niece

Lyra Estella Black- Sirius sister