How do I customize a label?

[mygcc]

I'd like to create customized labels for our checkins, where we are able to change the following info:

Children's Tag as is, but:
Add the age of the child.
Print only the first name of the child.

Parent Tag as is, but:
Print first and last name of child, not just first name.
Print class name.

What is the best way to do this?

[Tracy]

The age is not available to add to the label.

When the child's last name is different then the parent the design is it will print.

John and Mary Doe have two children they bring to church. Henry Doe and Susie Queue.
Mary checks in both Henry and Susie. The label should show Mary Doe with the children of Henry and Susie Queue.