WordNet sense 1 (a person who is present and participates in a meeting):

attendee, attender, meeter

WordNet sense 2 (someone who waits on or tends to or attends to the needs of another):

tender

WordNet sense 3 (an event or situation that happens at the same time as or in connection with another):

accompaniment, concomitant, co-occurrence

WordNet sense 4 (following as a consequence):

incidental, accompanying

WordNet sense 5 (being connected either logically or causally or by shared characteristics ):

related, related to

WordNet sense 6 (being present (at meeting or event etc.)):

attending