SOLVED. Chapter book, adopted girl with Old English Sheepdog and spoiled cousin [s]

[Diana]

I have been seized with the desire to find this book I read in grade school (around 1993). Here's what I remember:

-It's a children's chapter book, probably an Apple paperback, probably part of a series
-Published around the late 80s/early 90s
-The main character is a tween girl. Let's call her "Mary" (probably not her real name)
-She is adopted and at one point someone makes a dig at her about this means her parents must treat her like a china doll
-She has an Old English Sheepdog that she takes everywhere
-"Mary's" kind of a tomboy, but her high-maintenance cousin (I think I remember her name being something like "Gigi" or "Fifi" but I could be wrong) comes to visit her for a while and drives her crazy at first
-Despite "Gigi's" spoiled nature, Mary's parents want her to be more like Gigi as far as taking care of her hair and clothes.
-Gigi checks out a bunch of romance novels on Mary's library card, and puts them in a bag for her to return them. When Mary gets to the library, she finds that Gigi has been reading them in the bathtub and they are all water damaged and she owes the library a ton of money.
-At some point, I think on Halloween, Mary, Gigi, Mary's dog, and possibly some of Mary's friends go out (trick or treating?) and get lost in the woods. They are there overnight and have to take tiny bites of a candy bar in order to feel full
-This experience brings them together, and when Gigi has to go home, Mary is genuinely sad to see her go

[Tab]

Meet Miss Dracula by Molly Albright sounds like it.
About the Book
Though she tries hard to be friendly and understanding, twelve-year-old Missy finds it difficult to get along with her sophisticated cousin from New York.

It's from the Two of a Kind series
You can read/see the cover on OpenLibrary
https://openlibrary.org/works/OL46240...

[Diana]

This must be it, thanks!