All I know is, Rick Reardon appeared in both groups. See bottom credits on Ambassadors 'B' side for vocals...
7 Dwarfs - Sharon Herr(also on Keyboards),Rick Reardon,Ronnie Keene,John Helm and Jerry Ransing and with band members Denny Groff on guitar and Charlie Evans in Percussion.
Ambassadors - Bill Parmer (bass), Bobby Bitts. (drummer), Bob Weaver and Mike Sultzbach (sax), Tony Purcell (trumpet), Don Hodgen & Rick Reardon (vocals), Burton (piano), Eric Spitzer (guitar).