Originally Posted by
stifle
You will need to have the JFK-MIA on a separate ticket to the others as putting more than one non-BA airline on a BA award ticket results in the award being priced on an extremely expensive all-partner award rate.
I don't think this is true anymore - since November 2011 BA price all awards segment-by-segment, with all rates the same regardless of what airline you're flying. There are no longer different rates for BA awards, single-partner awards, multi-partner awards, etc.