All you need to do is to separate the one group you want to specify on your right axis into one column and all others into a second column. In my example I have separated out the heights for individuals of age 14
This can either be done as real columns
Using the formula for the column "Most Heights"
If( :age != 14, :height, . )
Name the formula for "Height 14"
If( :age == 14, :height, . )
Or the columns can be virtual columns by just adding them to the Graph Builder definition....using the same formulas as above
Jim