From what I've seen via credits: Wanda Sá's Brasil '65 album featured the Sergio Mendes Trio and Rosinha da Valença; Bossa Nova York aka The Swinger from Rio; and In Person at El Matador all feature Chico Batera on drums (with Tiao Neto on bass, except for the latter album, which I haven't yet seen a listing for the bass). Two other early Mendes records had Edison Machado on drums rather than Chico Batera. The Great Arrival marked his arrival in Los Angeles, and I do see Romao credited for Favorite Things and Joe Mondragon on bass (no credits on The Great Arrival). Cannonball Adderley's album With the Bossa Rio Sextet of Brazil has Dom Um on drums and Octavio Bailly on bass (who, if the credit is correct, was also the bass player in Sergio's Bossa Rio spinoff for A&M and Blue Thumb). If anything, Tiao Neto was with Sergio from the earliest days, whereas Dom Um seems to be on the later albums, with both rejoining Sergio for Fool on the Hill. Unless some credits are missing, I don't see the two playing together with Sergio (on record, anyway) until that point.I have two of the Atlantic albums that Sergio Mendes had with them-Great Arrival and Favorite Things. The former does not list personnel other than arrangers. The latter does(1968) and Dom Um Romao is listed for drums. I think he was from Trio but I am not 100% sure on that.