touring member

plural touring members

1. entertainmentA person, not credited as a full member of a music group, who performs as part of the group while it is on tour

   Pino Palladino, the Welsh bassist ... who is now a permanent touring member of the Who.

   2009 June 14, Graeme Thomson, “Pop stars anonymous”, in The Observer, London

   2 more examples

   White was a touring member of Green Day from 1999 until 2012, playing lead guitar at the majority of their live shows. In late 2012, he became the official fourth member of the band.

   2014 December 6, Brian Kraus, “Green Day guitarist Jason White diagnosed with tonsil cancer”, in Alternative Press magazine

   After playing on many Beach Boys sessions, Mr. Campbell became a touring member of the band in late 1964, when its leader, Brian Wilson, decided to leave the road to concentrate on writing and recording. He remained a Beach Boy into the first few months of 1965.

   2017 August 8, Michael Pollak, “Glen Campbell, Whose Hit Songs Bridged Country and Pop, Dies at 81”, in The New York Times