Feed locations of multiple feeds binary distillation column?

Question

I have a binary distillation system with 2 feeds (different compositions).
Firstly I did the step-off stages with the McCabe-Thiele method and found out that the number of theoretical stage required is 16.
After that I find the overall efficiency with O'Connell's correlation, which is ~50%, thus the actual stage required is 32.
Then how do I determine the feed locations of those 2 feeds?

Answer 1

OK, better be careful with my answer but this is how I would do it. When you stepped off the theoretical stages you also know the concentrations at each of the theoretical stages. So I would match as closely as possible the liquid concentration at the stage with the feed concentrations.

Then using your 50% factor determine the actual stage.

Answer 2

1