I am taking three 11-15 year olds to London for the weekend and trying to work out how I navigate the tube with them as I would usually just use contactless card for me to tap in and out. I have read that I can buy a visitor oyster card and add a child - does anyone have experience of this? Can I add all 3 of them to my one adult card? And then how do we tap in and out at stations - will I be able to tap for all of us or is there a different method? Thanks!