CB child born abroad passport question please.

Hi,
I tried to find the answer in the posts but i wasnt successful.
I am applying for Child Benefit for my child born abroad and the form says:
"If any child in this claim was born outside the UK we also need to see their passport(s) or their travel
documents used to enter the UK."
My child has three passports since we moved to the UK and I am not sure which one should I send with the application. The one she used when she first came to the UK 6 years ago (which is expired now) or her recent passport which has no stamps since she hasnt travelled abroad after renewing her passport.
She has a indefinite leave to Remain biometric card. Would that suffice?

Thank you for your help.

You need to send the current passport. If they want the original entry passport, they will write to you.

I called the child benefit helpline about this. They want to conclusively establish that the child entered UK. So they want to see the passport used to first enter the UK.