Daas Yochid,
Im Al Hamelech Tov Ve’im… I usually can’t read Hebrew here, since I’m using a phone. If it isn’t so much more of a Tircha, can I ask that you try to use transliterations wherever possible?
Anyhow, no matter what the reason for lighting an extra for each child, it is definitely not a Ner Neshama. You are not being Motza them, just like the first two are not for the husband and wife.