A family of ghosts save their manor (possibly) or castle by putting on a haunted ghost tour with the help of the living person that can see them

It reminds of the Ghost tv series. I remember there was a skeleton like soldier ghost who could partially materialize, and another ghost who could take off his head. All of the ghosts had powers like in the tv show. I don’t remember if the main character (person who moved into the manor) was a guy or girl.

The cover of the book had a picture of an old iron gate with some ghosts standing around it. But I can’t find it anywhere