Lookup Issue with Duplicate Data

Hi,
This is my second Term scheduling with this template and I wanted to make an adjustment so that when

There are about 10 Courses, primarily each Course has 7 lessons (some may have a few more) and the titles of the classes change frequently while Im scheduling. Last Term, I had a two drop boxes the first selected the Course "PostProduction1" and the second was dependant list with the lesson "4.Dramatic Lighting and Advanced Depth Techniques" based off the list on another sheet. But when people wanted to change the lesson name I had to first change the name and then go and reselect the new title to get the rest of the info to fill in (Room, Instructor, Groupings).

So this term I was hoping to select the Course "PostProduction1" and the second would be a dependent list with the lesson numbers "1-7" and then the lesson name, room, instructor, groupings would fill in from a lookup. But because theres duplicates I cant seem to figure out how to do it. Ive tried different monikers that I could think of for numbering the lessons but now its become both cumbersome and still hasn't really worked.

Only cells c5:c11 d5:d11 have the correct formulas (I added a line to everyday and haven't fixed everything yet) and Ive only been testing Post Production and Producing 2 and 5.

Is there a way to have the lessons named 1-7 instead of the more complicated PP5L2?

Thanks in advance for any direction!

Thanks so much, this totally fixed it!