What you need to do is make it clearer. This is fairly simple. Let's start with the first one.
1.) Becky told Kristen that her office will be painted.
Clarify whose office will be painted. You can do this by adding one of the girl's names again into the sentence.
1.) Becky told Kristen that Kristen's office will be painted.
Let's try the others.
2- Stephen, his brother, and his father recevied invitations to Stephen's graduation.
3- Fraddy has a wrench, a table saw, and nails, which will all be useful in shop class.
4- Mirabelle told Candace that she saw Candice at Mirabelle's house yesterday.
5- Jim and Don disagreed over who should paint Jim's room.
6- Cheryl talked to Ms. Smith about Cheryl's illness.
7- Dan told Zack that Zack's garage door was open.
