Complex sentence: During the late 1990s/early 2000s, several new members joined TRHS while some older members became inactive and no longer performed or taught classes, but were still members of the dance company.
Split into simpler sentences: During the late 1990s/early 2000s, several new members joined TRHS. Some of the older members became inactive and no longer performed or taught classes, but were still members of the dance company.