Ideas to include
The bride's greatest hits
The ex nobody mentions at dinner, the legendary night out, the phase she pretends did not happen. Everything the group knows and the groom does not.
From all the bridesmaids
One memory from each of them, one song from all of them. Easier to organize than a group speech and considerably harder to forget.
The one soft verse
Ninety percent chaos, then one honest verse about her getting married. Ask for it explicitly. It is the reason she keeps the file.