Recording falsetto

[HapiCmpur]

I've written a couple of songs recently that require me to shift into falsetto for occasional lines and phrases. (It's intentional, so I don't want to "solve" the problem by transposing the song into a lower key.)

Anyway, I'm having trouble getting a satisfying falsetto sound. When everything's set so that the main vocal sections sound good, the falsetto sections are weak, and vice-versa. Just leaning into the mic for the falsetto sections isn't working. (Shocking, huh?)

Am I going to have to record the falsetto sections on a separate track and then splice the two together? If so, it's probably not going to sound seamless. What are some other options?

For clues, I've been listening to John Mayer's "Room for Squares" and am impressed with the way his vocals (and everything else) are recorded, especially his seamless slides into falsetto. How the hell do they do that? You can tell that his natural voice is thin and breathy, but his recorded voice is strong, fat, and right up front, even though it maintains the natural breathy characteristics. Sometimes he even sounds like he's whispering, but there's no drop in volume or clarity. Are his sound engineers doing anything that I could approximate at home?