--Steves review has a chart on what the various flashes can and can
not do.
Looks like no ratio flash from the camera.
http://www.steves-digicams.com/2003_reviews/a1_pg2.html
I have a single Sigma 500DG Super flash unit (very similar to Minolta 5600). If I'm reading the manual correctly, you can perform ratio flash is you have two units (I believe that a wireless Minolta could be used as the second flash). I was able to set the Sigma as a "controller" unit (on the camera) and set it for 1:2 ratio flash. I believe that the second unit (wireless one) would just need to be set for the same channel.
JC