Getting the sb600 and ab800 to work together.

TonyG

I am currently using two sb600s triggered by the onboard flash of my d90. As for living in sunny south florida I am not getting enough light out of them in outdoor situations and would like to upgrade to ab800s but still use one or both of the sb600s as a background fill or a highlight flash. What would be the simplest or easiest way to get all four to work in unison? Also since moving up to a 5d is in the near future what would I have to change up to get this setup to work with a canon? Thanks again.