You said Viscount last time. Did he get promoted for something?

Anyway, nitpicking time: this styling isn't correct. I'm going to assume that the Earldom Macross was created to devolve upon the heirs general (so it's probably Scottish) - rare but not unheard of - so she can inherit despite being a girl. Regardless, she's not a "Miss" if she's a Countess. The proper styling in speech would be "Lynn, Lady Macross", or in writing, "The Right Honourable The Countess of Macross". As a peeress, she would never be referenced using her family name of "Mayminster"; the family name is used only for children of peers who are not heirs, or children of low-ranking peers. She would sign her name as "Lynn Macross".

Before her father died, she was "Lady Lynn Macross", as the eldest daughter of an Earl. She would have been "(The Honourable) Miss Lynn Mayminster" while he was a Viscount, if she was born back then.

>Lieutenant Commander the Honourable Lisa Hayes, RN

Where did she get an Honourable from?