sync signal on parallel DC/DC-Converters
You're right about driving different converters (power trains) with different phases of a master sync clock.  Doing so increases the ripply frequency on the output and thus makes it easier to filter.  We design/build SMPSs with multiple power trains (2 &amp; 4 being the most common) all the time.
But in your case, you need to make sure the individual converters allow themselves to be connected in parallel.  If they do, it should be so stated on the data sheet.  If not, you run the risk of one converter trying to supply all of the load current.  I skimmed through the data sheet for the converter you referenced and did not see any discussion about operating converters in parallel.