In 1995 Waxahachie, Texas, PAULA HARRIS, her husband TRAVIS, and their children--MELINDA, ANTONIO, and TASHA move into an allegedly haunted house. They are informed by the realtor and neighbors that a family named the Watsons were brutally murdered in 1970 in the house.
A couple of months later, the family finds the Watsons’ evil spirits are trying to force them out of their home. The spirits still think the house belongs to them and they want to retake ownership of the house. The deceased wife/matriarch of the Watsons [Watson?] family murdered her entire family and committed suicide after she discovered her husband, the love of her life, had an ongoing affair with their children’s nanny.
Paula and her family learn that [all] the previous owners either fled, disappeared or were murdered. The deceased wife possesses Paula’s older daughter, Melinda. Paula gradually notices that [her eldest daughter] Melinda is acting very unusual. She finds out that [Turns out] the deceased wife is controlling [has possessed] Melinda. For a while, they [the Harrisses (or is it Harrises?] ponder whether to stay or leave the house. They decide to stay and get rid of the spirits.
At first, Paula and her family think they defeated the spirits after they [arranges to] have the house blessed by a priest. [and] All of the paranormal activity stops. The house is peaceful for a while[--] until the spirits come back with a vengeance and try to kill them all. Later, the deceased wife possesses Paula and forces her to attack her family. After getting [she gets] into a fight with Travis, he acts as if he is going [feigns trying] to kill Paula which in turn scares the deceased wife and she leaves Paula’s body.
Everything in the house begins to move as if an earthquake hits it. When the Harris family sees that the evil spirits have come back and grown stronger and that there is no way to get rid of them, they decide to leave their dream home permanently. Weeks later, they buy a new house in the same neighborhood. [Good idea. Let's live down the street from the spirits who want us dead.] Instead of destroying the [haunted] house, the realtor sells the house [it] and the new owners turn the house [it] into a museum. [Presumably a museum that isn't open at night.] [On second thought, nighttime is the only time anyone would want to go.] [So that's it? After resolving to fight for what's theirs, they give up and leave? It seems like the ghosts are the main characters, and they learn to be careful what they wish for, as they were better off with the Harris family than with all these tourists visiting every night and demanding a horror show.]
Finally, the story flashes to the present and at this time, Paula, Travis, and their now grown children dine at their favorite restaurant and reminisce about everything that happened to them over the years. They talk about all of the latest events in their lives before they leave separately for a planned get-together. [This isn't needed in the query. It probably isn't needed in the book unless something startling happens at the dinner, like the waitperson turns out to be Mrs. Watson.
On the TV show Supernatural, now in its twelfth season, when a house is haunted, it's almost always haunted by ghosts of people who were murdered there. Which I mention only because this book is called The Supernatural. (See previous post.)
I've suggested some lines I think you can do without; whether you want to replace them with other lines may depend on how long a synopsis you need.