We recently used H&R Block Online Tax Software to file our Federal and Maryland taxes. What I didn't realize was that H&R Block does NOT support Maryland taxe questions regarding Maryland 529 (contributions to our Grandson's College Investment Program). After I filed I realized the program didn't ask me whether I had any Maryland substitutions related to Maryland 529. Now, I need to know whether I can send in an amended return without filling out the entire Maryland return again, by using the MD502SU form. Can I just fill in Pg2, line xb with the amount my wife and I contributed?