If you go to tools, house keeping scroll through. I think it's update telephone numbers. This is where you can see all the contacts for a child and can change prority and which number is used, this includes email addresses. I used to check it regularly due to the amount of changed mobile numbers parents seemed to have.
You can can also choose that no number is shown for contacts. Useful if you have to copies of correspondence to an estranged parent but do not contact them for any other reason.