Complex sentence: Peter Griesar was a bartender at Miller's beginning in 1989 and in August 1991, during Miller's annual respite for inventory, Matthews, Beauford, Moore and Lessard used the empty bar for rehearsing.
Split into simpler sentences: Peter Griesar was a bartender at Miller's beginning in 1989. In August 1991, during Miller's annual respite for inventory, Matthews, Beauford, Moore and Lessard used the empty bar for rehearsing.