forms - How to indicate that one of a group of fields is required

I have a form where there are multiple fields. Some fields are required, and I have an asterisk next to them in red color. There are some fields where one of them is required. For those fields, I have put double asterisk (**) next to them.

Here's where I need advice: There are 2 parts of the form where I have double asterisks. So let's say the user has to provide contact info: either email, cell phone, home phone, or work phone. All of those fields have ** . And then in another section, the user has to provide either parents' email or parents' home phone. These fields also have ** next to them. I have a legend on the top of the page which says:

*Denotes required field.
**Denotes one or the other field is required.

It can be confusing to the user as to which one of the fields is required, as the legend is red in color for both single and double asterisk fields. Should I assign them different colors to mitigate confusion, and add that color to the legend? What color is appropriate?