Citizenship for children born abroad.

Good day

Parent (father) British citizen by naturalisation.

2 kids :

One born before father became British citizen (2022)
One born after.
Both born abroad.
Both under 18 y.o

Can the father register them as british citizens and how ?

Many thanks.

The child born AFTER you became British is a British citizen by descent and can apply directly for a passport.

The child born BEFORE you became British, has no entitlement to register as British. Where does this child live, in the UK or abroad? What is the child's UK immigration status and the immigration status of the other parent? How old is the child?