1960s/70s YA series about a girl who lived in NYC and explored alleys, solved crimes

[Elizabeth]

In the second book her family moves to Southampton NY, where there are no alleys, but mysteries to be solved. She fell asleep at night by making up stories about her imaginary future life.

[Kate]

Elizabeth, you can bump your thread every month or so. This keeps your thread near the top of the folder, where fresh ideas might crop up.

When did you read this? When, approximately were the books published?

[Lobstergirl, au gratin]

Elizabeth, are you still looking for this or did you find it?