There really isn't any way to change the BPM of multiple masters at once. But, if you consistently run these chases together then you could try this:
Disable chase on the two individual cue lists
Record a third cue list with two blank cues and add GL macros to those cues that trigger the other two lists
You can then use tap sync on that third dummy list to change the rate of go's on the other two masters.
Not the best solution as I realize you might want chase the lists individually at times as well; but it's a start.