Help Me Find This YA/Childrens' Book?

When I was around nine or ten, I came across this novel tucked into a corner of our attic. I must have read it a hundred times, but can’t for the life of me remember the title or author.

I’m almost positive the main character’s name is Imogene or some variant thereof, and I think that name is in the title. Imogene is around 13 or 14 and is somewhat of a misfit among her peers [think Wednesday from the Addam’s Family]. Her mother is an artist and decides to leave Imogene with her father/grandfather/assorted aunts and uncles who live in a dusty old mansion on the outskirts of town. Imogene’s father/grandfather own and run the town’s department store. The store figures in significantly later when Imogene, bereft at having no friends, decides to steal a mannequin and pass it off as her best friend [or sister maybe?] at some event or other at school. The book ends with her mother returning from the artist colony to take her back to New York [I think].

Does anyone have ANY idea what the title might be? I’ve Googled for ages and can’t find a thing. TIA.

“Irma” not “Imogene.”

The Bad Times of Irma Baumlein" by the great Carol Ryrie Brink.

THANK YOU THANK YOU THANK YOU!

I’m off to Amazon as we speak!

Glad to help – hope it’s as good as you remember!