Children born in UK before mother's UKM registration

[aledeniz]

A grandmother was British, born in UK, she married an Italian citizen, and moved to Italy.
The grandmother's children were born in Italy, and gained Italian citizenship at birth through their father, the grandfather.
The grandfather died, and the grandmother moved back to UK, taking the children with her.
The mother, daughter of the grandmother, was born in 1979 in Italy, so she was not given British citizenship in 1983.
The mother has married an Italian citizen as well, and they have children, all born in UK, who have all lived in UK all of their life, but are all Italian citizens.
The mother and the children are all legally residing in UK as Italian citizens, e.g. exercising EEA treaty rights. At this point in time they all have settled status, although none of them has yet certified that through EEA3/EEA(PR).

If the mother registers as British citizen by descent through the form UKM, what happens to her children? Do they automatically become British citizens at birth, even though the registration of their mother will happen well after their birth?

[secret.simon]

Do they automatically become British citizens at birth, even though the registration of their mother will happen well after their birth?

Registration as a British citizen is prospective and not retroactive. As the mother was not a British citizen at the time of birth, the children can not inherit a status that was not there.

If they have been born in the UK and are still minors, they are entitled to registration under Section 1(3) of the BNA 1981, using Form MN1.

[LilyLalilu]

Or registration using form T if they have been born in the UK and can show that they lived here until age 10 (in case they are of age).

[Richard W]

And any of the children born after a parent acquired settled status will have been born British.

[vinny]

When were the children born in the UK?

[aledeniz]

When were the children born in the UK?

2004 and 2007.

Given the answers above (thanks to everyone), it looks like for the 2004 child the only available avenues are registration through MN1 or T, while the other one should already be a citizen by birth.

As a side note, my view is that the current legislation for this scenario should really be amended.

[secret.simon]

As a side note, my view is that the current legislation for this scenario should really be amended.

It is the current mess because well-meaning MPs and peers have amended it retrospectively so often. Less amendment (and less sentiment) would be better, in my view.

the 2004 child the only available avenues are registration through MN1 or T, while the other one should already be a citizen by birth.

Why is that? Did either the mother or father acquire settled status and if so, when? Was it through ILR (pre-2000) or through PR under the EEA Regulations? Remember that PR requires proof of exercising treaty rights, which is more specific and more demanding than mere residence.