Conversation so far:
What happened in 1940 to Fred Astaire?
In the 1940s Fred Astaire was drifting to an early retirement.
What Broadway shows were Fred Astaire in?
The Fred Astaire broke into Broadway in 1917 with Over the Top, a patriotic revue, and performed for U.S. and Allied troops at this time as well.

Question: Who else did he perform with?
Self-contained rewrite: Who else did Fred Astaire perform with besides his sister did he perform with?