why do we say C, L, E in this sub

I’m new here so I might have missed why, but why does everyone in this sub call her daughters by their first initials? Like you can’t even write their full names in this sub…? Everyone knows their names and she even did a recent TikTok including each of their names and why she chose them, she even says that none of them have middle names. So I don’t understand? What did I miss?