She worked for two years as a teacher in Nelson and married her second husband, Stephen Lunn Müller, a surgeon and a fellow immigrant from Britain, there in 1851.

She also began to write articles on the topic of women's rights, which her friend Charles Elliott, the editor of the Nelson Examiner, published in his newspaper.

Müller's argument was that it was necessary for women to obtain the vote in order for them to contribute fully to the progress of the nation.

She also asked for the repeal of discriminatory legislation, and appealed to men – particularly members of Parliament – to take up the cause of women's suffrage.

Unwilling, because of her husband's position, to become a public activist, Müller nonetheless met William Fox in private to discuss her views.