When adding band members to their profile, provide artists with the option to tag another Bandsintown profile as a member.
Such a tool would be fantastic for the indie and jazz communities, where individual players perform in multiple groups. Once linked up with all of their bands, these musicians would be able to generate widgets for their personal websites without having to add their show info manually. Such linkage could also help the Bandsintown recommendation engine; if you like one band that a performer plays in, you might like the other band they play in, too.
When adding a Bandsintown profile as a band member, a request could be sent to that Bandsintown profile asking permission to link pages. The Bandsintown profile would then approve or deny the request.
Conversely, an individual artist could list the bands of which they are a part and tag those corresponding Bandsintown profiles. If those bands request access to the individual, the profiles could automatically link.
The ability to allow or deny such linkage requests could be offered as a settings toggle, with the default set to "deny" (this way nobody would be able to request, for instance, Taylor Swift as a band member unless she toggles this setting to "allow").
Please see attached for an example of an artist for whom such a feature would be extremely helpful.