After the initial concert, bands often expand their lineups to enhance their sound, accommodate new musical directions, or replace departing members. The search results provide several examples of how bands have expanded their lineups:
The Band, a Canadian-American rock group, initially formed with a core group of members and expanded over time, incorporating additional musicians to enrich their sound. The Band - Wikipedia
Linkin Park reconvened after the death of their lead singer, Chester Bennington, and introduced Emily Armstrong as their new lead vocalist for their first full performance since the tragedy. Linkin Park Does First Full Show Since 2017 in L.A.: See Full Setlist
The Police solidified their lineup a few months after their first gig, with Sting, Andy Summers, and Stewart Copeland becoming the trio that defined the band's sound. The Police - Wikipedia
These examples illustrate that bands may expand their lineups by adding new members with unique skills or by finding replacements for members who leave. This strategy allows bands to evolve musically and continue performing at a high level.