I know what to do!
In my world vampires CAN age! Well, up to a certain point (20 maybe), but they can age.
The beginning of the book will be child vampires (Ann 10 and Roland 12).
The middle on up they will age just a bit (Ann 14 and Roland 16).
I'm going to work it out into the book.
It's frustrating being back i the edit stage, but now that I know why it gets rejected I can do something about it!