Youngest Child Opens Presents First
This isnt fair to the oldest child... forever. As they get older their spouses/ gf feels awkward and put on blast for being older. This one needs to be retired. Know your audience.
Start With Youngest Child For Christmas Gifts
Bad idea. Its not fair to the oldest... forever and keeping it till they are older just makes things super awkward for their respective spouses/ girlfriends who do not want their age put on blast. Its so rude to demand to know ages.