The tallest boy is Dick Grayson (Nightwing, Robin, Batman). The next tallest is Jason Todd (Robin, Red Hood). After that is, of course, Tim Drake (Robin, Red Robin). And then, finally, Baby Damian Wayne (Robin). The dark haired girl is Cassandra Cain (Batgirl, Black Bat), and the blonde is Stephanie Brown (Spoiler, Robin, Batgirl). I hope that helps, and if it didn't, sorry for filling your mailbox/comment section.
I have to ask, are you aging them based on their year of origin? Because if you're not then I feel that I need to inform you that Cass and Jason ARE the same age. Just FYI, I think the artwork is adorable though.