UCC28710: Regulation of the multi-output

Part Number:UCC28710

Dear all.

I think about the multi-output by flayback.
Our customer made the following transformer.
inductance : 700uH
Turn ratio (24V output) : 2.69:1
Turn ratio (12V output) : 5.38:1
Turn ratio (3.3V output) : 17.5:1
Feedback is 3.3V.
I want to get good cross regulation of 12V and 24V, what kind of method is there?
I am understood that the output voltage changes to some extent because Duty changes.

Reagrds,
PAN-M