Another (or Two) GLBT Character on "Mad Men"

Following Bert Cooper's luncheon with his sister, it was evident that she is a lesbian.  "She's a good companion, isn't she?  However, his sister, mentions "Don't you want to go to Montana?  You ruined that poor architect's life.  Go visit your cattle."

So, are we to believe or assume that there is not only one, but two additional GLBT charachters in the "Mad Men" universe?  Given Bert Cooper's proclivities towards the art and a more gentle way of living, it wouldn't surprise me at this point. 

Any speculation?