Kids book (might be series) about group who solves crimes. In one instance they save a popular movie star.

[Maria]

I read two books from this series around 2002-2004 and it was about a group of friends. (Possibly a girl and two boys) who solved crimes.

In the first book the girl follows around this movie star and finds out he is being blackmailed. The group befriends the movie stars daughter. At some point in the book they have fish sticks at the movie stars home.

In the second book the group is at camp and there is another crime they solve. Dont really remember much from this one.

[Kris]

A long shot - Dangerous Loves by Carolyn Keene from the Nancy Drew Files series?

Maria, how old are the kids?

[Maria]

Sadly thats not it. They must be 12-13. There was something about a letter made from magazine cut letters also...

[Asia | Adventures with Asia Minor]

So it's not any of the Nancy Drew series? A to Z Mysteries? Calendar Mysteries?

Do you know how many books are in the series?

[Maria]

Not any of those. I’m not sure now it was a series but I read two for sure.

The blackmailed actor who was from england and the kids befriend the daughter, and the one at the camp. I believe there were diamond smugglers or something like that!

[Asia | Adventures with Asia Minor]

Do you think it could be a short series, like, less than 10 books or 5 books?

The magazine cut letters . . . are they in the title or part of the plot/book?

[Maria]

It could be 5 or so. Or maybe just those two I read. The magazine cut off letter were in the plot as part of the blackmailing letter.
Another detail i remember is the kids and the daughter of the actor eat fish and chips at his home/mansion.