Francophone people often have prénoms composés, and I am told that the two hyphenated parts both compose one name and that I shouldn't address Jean-Jacques as Jean or Jacques, for example.

The question is whether this is also true between close people, like between family members. Does a mother always addresses her son as Jean-Jacques, not using shorter nicknames? If they do use nicknames, which part of prénoms composés are they often based on?

Thank you for your help in this matter.

Francophone people often have prénoms composés, and I am told that the two hyphenated parts both compose one name and that I shouldn't address Jean-Jacques as Jean or Jacques, for example.

The question is whether this is also true between close people, like between family members. Does a mother always addresses her son as Jean-Jacques, not using shorter nicknames? If they do use nicknames, which part of prénoms composés are they often based on?