Flo and someone (probably Marion her sister) dressed up for a party.
I found this tidbit about a 1912 “cross-dresser”:

The piece is suitably enigmatic. I’d would have guessed we have a McGill Student here, but the guy was from Liverpool. A sailor?
And the man’s age is not given. He is arrested for being drunk and disorderly, not for impersonating a woman.
You see, in that era, in many North American jurisdictions it was against the law for a woman to dress as a man.
That’s why the new ‘harem-skirt’ fad was proving so titillating. Was it a skirt? Or was it a pair of pants?
A young woman had recently stopped traffic on the Brooklyn Bridge wearing harem pants.
If that’s Marion Nicholson, dressed as the male in the family pic above, it’s not surprising. She often signed her letters M.A.N Esquire. (Marion Annie Nicholson.)
Marion went on to marry and have four children, and many grandchildren, one of them my husband.
She was widowed in 1927 and went back to teaching, rising to be President of the PAPT Union, fighting for better salaries and pensions for women teachers. She never remarried, but had a boyfriend. She died of a heart attack in 1947, just before retiring so she never received a pension herself.
Post WWI, war veterans in England dressed as women in front of Parliament to protest their shoddy treatment upon their return home. It was a symbolic act to imply they weren’t being treated any better than women.
In cabaret and Vaudeville acts big men dressed as their womenfolk on stage and created the ‘battle-axe’ cliche. It was their way to get back at these strong matriarchs, who wielded a lot of power over them.