Will you change any load suddenly? Because if one load changes suddenly on one supply, the other two supplies will change suddenly. This is something to consider in your design. Perhaps you plan to put regulation on all three supplies?
So it looks as though that is four windings you're talking about? I believe you will need to do a lot of winding and unwinding turns, in order to get all of them right.
My load is fixed as mentioned.
Efficiency is 96% as per calculation.
But I hope I can achieve something in between 90-96%
In that way I can accept few percentage of regulation too.