Never Hit a Ghost with a Baseball Bat by Eth Clifford, 1993.
Mary Rose and Jo-Beth are visiting another museum with their father, but they’re not happy about it. Mary Rose is annoyed because there’s a boy she likes, and no matter what she does, he just won’t pay attention to her. Jo-Beth is annoyed because she just turned eight years old, and well, . . . she just turned eight. Nothing special happened on her birthday. She doesn’t look different, she doesn’t feel different, and she just had to go to school like normal. Their father, Harry, hopes that a visit to a strange museum dedicated to antique trolleys will help snap them out of their funks, although neither girl thinks so at first.
But, it seems like the trolley museum might be inhabited by a ghost. The owner, Sam Thorne, doesn’t think so, but his assistant, Hoot Turner, can’t think of any other explanation. Strange things are happening. Food and other objects disappear. Things are moved around. Areas are . . . unexpectedly tidy? What gives? If it’s a ghost, it’s apparently a ghost that believes in cleanliness and doesn’t mind doing the dishes. But, if the ghost is so friendly and useful, why do mysterious voices call out to them to beware?
The girls explore the trolleys parked in the museum and admire the manikins dressed in old-fashioned clothing that are part of the displays in each trolley car, but more strange things happen. A teddy bear seems to speak to them, even though it isn’t the kind with a string and a talk-box. The manikins start to seem creepier. Mary-Rose and Jo-Beth are only armed with a baseball bat from one of the displays and the old teddy bear (which terrifies Jo-Beth). But, Mary Rose is determined to find the ghost, even if it’s the last thing she does!
Telling you about one of the themes of this story would spoil the ending, but both the girls come to realize that there are people in the world with much more serious problems than the ones that they were worried about at the beginning of the story. There is a happy ending for everyone as Mary Rose turns her mind to something more interesting than a boy who takes no notice of her and Jo-Beth appreciates her birthday more by throwing a special party for someone else.
This is part of the Mary Rose and Jo-Beth Mysteries series. It is available to borrow and read for free online through Internet Archive.
The Dastardly Murder of Dirty Pete by Eth Clifford, 1981.
Harry Onetree and the girls find a ghost town with a hotel, an opera house, and several other buildings. Although Harry only means to look around for a little while, he forgets to set his parking brake (something else Mary Rose warns him about, which he ignores), and their car rolls backward into a ditch. Since it’s getting dark, they’re stranded in the ghost town for the night. But, they’re not alone there.
Scared Silly by Eth Clifford, 1988.
While the Onetree family is visiting the museum, a pair of shoes that once belonged to a Chinese emperor disappears. Like the two Onetree sisters, Gus considers himself the sensible brother and doesn’t take Razendale, the dreamier sibling, very seriously. He thinks Razendale ran off with the shoes as a prank. But, Erik, who seems more sensible than either of his uncles, says that they can’t just accuse him without proof. Gus provides them with an invention that could settle the whole matter, but that depends on whether or not they can trust Gus.
Just Tell Me When We’re Dead! by Eth Clifford, 1983.
The first place he goes is to an island in the middle of the lake near his house. The island has campgrounds and an amusement park, which is now closed for the season. Mary Rose and Jo-Beth, realizing where Jeff has gone, follow him there. But, the children are not alone on the island. When Jeff is captured by two criminals who are looking for loot that they stashed on the island years before, he has to keep his wits about him to find a way to summon help. Meanwhile, Mary Rose and Jo-Beth have no idea what they’ve just walked into.

Be a Perfect Person in Just Three Days! by Stephen Manes, 1982.
The Dragon Charmer by Douglas Hill, 1997.
Then, one day, a rare crimson dragon comes to the farm and lays an egg. It is extremely uncommon to see a dragon’s nest or a baby dragon, and Dan is excited about trying to charm the baby after the egg hatches. However, Dan’s assistant is greedy and decides to steal the egg and sell it. Elynne overheard him talk about his plans before the egg was stolen, but because she wasn’t sure of what she heard, she didn’t tell anyone. Elynne feels guilty about not preventing the theft of the egg, and in spite of her fear, she is determined to get it back. In the process, she not only conquers her fear but learns about a talent that she never realized she had.
This is the last of the four books I have in this
Triple Trouble in Hollywood by Michael J. Pellowski, 1989.
Sandi doesn’t want to do it because it would be dishonest, but Randi and Mandy talk her into it. It’s partly to help Mandy, partly to get back at Tara for her rotten attitude, and partly for the chance to meet the heartthrob Judd Morrison who will also be in the commercial. Of course, as is always the case when the girls switch places, nothing goes as planned. But, to the girls’ surprise, their younger brother Teddy helps to make things better in the end.
Triple Trouble by Michael J. Pellowski, 1988.
But, Mandy’s snobbish attitude rubs Randi and Sandi the wrong way. Mandy doesn’t want to do anything because she might get dirty or break a nail, and she keeps bragging about how grown up she is compared with her not-much-younger cousins. The twins argue with their cousin, and they play tricks on each other. When Mandy takes advantage of acting skills and her similar appearance to the other girls to try spending time with a boy they like by pretending to be them, Randi and Sandi decide it’s the last straw! They decide to show Mandy that playacting is a game that three can play at.