Table of contents with multi-line chapter titles

I'm editing a book with multi-line chapter titles. For example, the first chapter appears in the text as:

---

Chapter I

The Four Basic Arpeggios

---

In the TOC, each line appears as a separate entry. I tried replacing the paragraph mark after Chapter I with a line break, but it didn't change anything. I'm going to propose two approaches to the author and let him decide:

a) Put them on the same line, as in: Chapter I: The Four Basic Arpeggios

b) Make the chapter line and title line separate styles and not include the chapter line style in the TOC; then put a number in front of the title, so the text would look like:

----

Chapter I

1. The Four Basic Arpeggios

----

Only the second line would appear in the TOC.

Does anyone have a better idea?