This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
a. I saw that movie with my younger sister.
b. Betty is my younger sister.
Could one use those sentences if one had more than one younger sister?
Do they necessarily imply that one has only one younger sister?
2. No, they may suggest, but do not necessarily imply only one younger sister.
Signature: Phil White
Non sum felix lepus