There are two ways of doing this - either from a NON-LINKED league or a LINKED league
In this scenario you really want to play out your season in DDS: College Basketball first advancing past the "End Season" stage there as that is when the PBDraft.rkf file will be generated. You need to copy this out of your My Documents/Wolverine Studios/DDSCBxx/Leagues/yourcollegeleaguename folder (or DDSCB/saves/yourcollegeleaguename folder if using an older version of DDSCB) and place it in the My Documents/Wolverine Studios/DDSPBxx/Leagues/yourproleaguename folder (or DDSPB/saves/yourproleaguename folder if using an older version of DDSPB). Then begin your offseason activities in DDS: Pro Basketball. After the d-league draft you will be given options to prepare the rookie class. Choose the File Import option and that will bring in your DDS: College Basketball draft class for the draft that will take place after your current pro season. After your draft is complete go back and play your next season in DDS: College Basketball and repeat the process.
These steps must be followed precisely
1. Create your DDS: College Basketball league, advance it past the Buy Reports stage at least and save.
2. Create the DDS: Pro Basketball league and link it to your DDS: College Basketball league during league creation.
3. Play some of each league making sure to save the CB league as you go because PB will automatically pull in updates on the players based on the saved game file.
4. When the seasons are over you must go past the "End Season" stage in DDS: College Basketball BEFORE you go to the "View Awards" stage in DDS: Pro Basketball because it is at that point the final rookie class is set and brought into DDS: Pro Basketball. SAVE your college league after the "End Season" stage BEFORE you "View Awards" in your pro league. Save your pro league after the awards.
5. Run the draft and offseason items in DDS: Pro Basketball up until you get to the rookie class creation stage.
6. Make sure you have advanced and saved your league in DDS: College Basketball past the report buying stage.
7. Once you are past the "Buy Reports" stage and saved in DDS: College Basketball then you can advance your league in DDS: Pro Basketball past the rookie class stage and go back to step 3.