Once again, ages have past since my last post. The wheels of discovery turn ever so slowly! But I'm pleased to say, there is a discovery!
In my book, I My Needle Ply With Skill, (available for purchase at the Saco Museum website ;>)  )
there are photographs of a small group of very attractive samplers that I speculated may have originated at the Gorham Academy, or perhaps in Portland, Maine at the female academy of Misses Charlotte and Sarah Paine who were from Limington, Maine--or just possibly in Limington itself, although Limington was (and remains) a rather small town. The samplers were made by Rosetta Libby:

who was born in Limerick, Maine but moved to Limington as a child;
Louisa Otis:

who was the youngest of the three children of Captain David Otis and his wife, Anna Small Libby, who was born April 7, 1807 in Limington; and of Mary Skillings.

Mary was born in West Gorham, Maine--the adjoining town to Limington--on May 10, 1816, the fifth of the eleven children of farmer Joseph Skillings and his wife, Susan Clark Skillings. She died, unmarried, on September 11, 1857. Her sampler belongs to the Baxter House Museum in Gorham. The others are in two separate private collections.
Now the Hubers have sold a fourth in the group!
This is the sampler of Julien Clark:

It turns out that she was also a Limington, Maine girl. It's very likely that she was Julia Ann Clark, who was the daughter of Nathaniel Clark, a shoemaker, and his wife, Martha Small of Limington. Julia died November 21, 1829, and given her place in the birth order of her family, was probably born about 1811. Later Nathaniel and his second wife would have another Julia Ann, but since she wasn't born until the 1840s, she is unlikely to be the sampler maker.

Given your now excellent sampler detective-ing skills, I know that you will need no prompting to see the elements that connect this small group of related samplers. Not all of the elements appear in each sampler, but there is sufficient commonality to make me quite convinced that the same teacher instructed all five girls. New owners of Julia Ann Clark--I would so love to hear from you!

I now think that since three out or the four girls were from Limington, the school was very likely located there. And even though the Paine sisters in Portland were from Limington, I now tend to doubt that they are the source since their school was said to have been rather expensive and none of these four girls came from particularly wealthy families, in fact, rather the opposite. 

I wonder how many more related samplers are out there? The Limington Historical Society is hot on the trail. Stay tuned for more discoveries!