See if this works the way you want.
Basically, I took the first data table, and added a new column that I called Score2, and placed the scores from the second study into that column. I also added a new column Treatment and added in the treatment group for each subject.
To create the graph, I dragged Score and Score2 to the Y axis, and Age to the X axis.
I dragged Treatment to the Color drop area
I then right clicked on the graph and selected Add=>Box Plot
Then I turned to the Properties area on the left for the Control Area.
For the Points, I clicked on the gray triangle next to the Variables listing to open the choices available for the Points and unselected the Score variable, because your request is for the Score values are not to be displayed as points.
For the Box Plot, I opened the choices and unselected Score2 and Color Treatment
Jim