Scared Silly by Eth Clifford, 1988.
Grandma Post has decided that Mary Rose and Jo-Beth Onetree are finally old enough and responsible enough to have an antique doll house that has been in their family for years. But Jo-Beth is irritated because her family thinks of Mary Rose as the responsible one, and Mary Rose doesn’t take her seriously. Jo-Beth is the dramatic one, a day dreamer.
Although Jo-Beth is determined to prove that she can be as practical and sensible as her older sister, neither she nor her father can resist a look at the Walk-Your-Way-Around-the-World Museum when they spot the sign for it on the way to their grandmother’s house to pick up the dollhouse. Practical Mary Rose thinks they should just continue with their journey and not get distracted, especially because the weather has turned stormy. Then, the bridge they had to cross over collapses behind them, washed away by rising river waters, so they have no choice but to keep heading toward the museum and call for help.
The Walk-Your-Way-Around-the-World Museum is a museum dedicated to shoes from different periods of history and different parts of the world. It’s owned by the eccentric Harper family, who also owns the strange house nearby called Harper’s Abode. Gus Harper made his fortune in shoes, and he’s the one who came up who built the museum. He’s also an inventor who creates magic tricks for stage magicians, and he decorated Harper’s Abode with them, almost like a funhouse. His brother, Razendale Harper, lives there, too. Razendale was an actor, and he now teaches drama and entertains children at the local hospital while wearing giant rabbit costume. Their nephew, Erik, lives with them, and Daisy Dorcet manages the family’s affairs.
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.
This book is a little different from the others in the series in that there isn’t just one issue that the girls consider along with the mystery. Jo-Beth considers whether or not she’s going to remain a dreamer or try to be more sensible (at least, part of the time, like maybe once or twice a week). Mary Rose is surprised that Jo-Beth can come up with some sensible solutions when she puts her mind to it. Then, there’s the shoe thief, whose motives are more altruistic than anyone suspects and who raises the question of where certain museum artifacts actually belong.
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.
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.
But, everything goes wrong when Randi’s coach talks to her teacher about the championship game, and it turns out that her teacher is secretly a soccer fan. When Sandi arrives for the tutoring session and the teacher and coach tell her the happy news that “Randi” can play in the championship game, Sandi has no time to tell Randi about it and switch places with her again. Will their hoax be exposed? Will the girls be able to switch places again in time to save the championship?
