I'm assuming the question is how to achieve vibrato on a bent note, as opposed to them seperately. I could do bends well first, then came a gradual vibrato, and lastly combining the two. But I found my usual vibrato not nearly as useful...it had to come almost entirely in the fingers in order to maintain the accuracy of the note. This requires another level of finger strength (and muscle memory).
However...I quickly (and gladly) referenced my recorded Pink Floyd concert from this last July, searching for a display of bent note vibrato. His normal vibrato came from mostly his fingers. Yet nearly every bent note they showed on camera, he used his strat tremelo instead. Not to say he doesn't ever use his fingers for vibrato on bent notes (although I didn't find one in my 3 song reference), but that tremelo usage is also a skill of it's own, and often overlooked and/or underestimated.