British Citizenship Application Form for Child with ILR

Dear Sir,
My wife and son got their ILR approved on 31st March, 2019. I also have my ILR approved on 28th February. My son is 11 years old and he was born in Bangladesh. None of us have British Citizenship. Now I would like to apply for my son's British Citizenship. Which form should I use? I know form MN1 can be used for children born in UK but which one for children born outside of UK and currently holding ILR?

Thank you

Now I would like to apply for my son's British Citizenship.

He doesn't qualify to apply for citizenship if he does not have ONE parent who is already British or who is applying for citizenship at the same time and the other parent holds ILR.

Which form should I use? I know form MN1 can be used for children born in UK but which one for children born outside of UK and currently holding ILR?

There is only ONE form, MN1. He doesn't, however qualify to apply yet.