I now know how to import rookies into your dynasty mode using db commander.
These are the steps
1. Once you begin your second season or any season besides the first one save your dynasty file and exit
2. Next open you db commander and find a rookie ones from the off season draft and replace that rookie from a rookie you have.
For example: You want to import Derrick Rose, find the rookie that is the 1st pick or any pick replace the playerpkg with Rose's pkg. For example DEROSE_.
3. Now you ask how do you edit his ratings, height, and other things.
Just use the db commander and edit those things.
This tutorial(kind of) doesn't explain how to do it very well(I know it sucks, I suck at explaining stuff), but I will release a video tutorial very soon showing how to do this!!!
I HOPE I FOUND SOMETHING USEFUL, and tell me if this was already discovered!!!