Mother’s Day Etiquette…Help Save Big Jim

Who is expected to participate in Mother's Day -- you know, send cards, candy, flowers, phone calls? I thought it generally was children of the Mom, and the father of the children to the Mom. Even a step-father to the Mom of his step kids. And maybe from a wider range of people when a woman is a new  Mom, like her friends, siblings, etc. Big Jim's plan was to take his "Live In" Girlfriend's children to pick something out for her, from them, not him? What do you think?  HELP.....