Hi rohan -
I don't think what you're asking for is the right solution... it would appear from your picture that the line and the bars in the top half are using dollars as units and the bottom line is using percent. If you were to try to put both of the 'lines' on the secondary axis, the profit ratio would ride the bottom of the view as compared to the other (would look very silly).
If both of the lines were percentages, you could use an aggregate measure for your bars, differentiating the color with some logic test placed on the color shelf... this would free up 'measure value' to use for as many lines as you'd like on the secondary axis.
Hope this helps!