Dependent Child allegation

Hi,
I applied for UK work visa from Pakistan after getting COS, my dependents are my husband and 8 years old son.
Today i received email from UK Decision making center stating that
-->You have submitted a birth certificate which was registered on 09/08/2023. This is 8 years after your date of birth. Please confirm why there was a delay and what evidence your parents were required to provide in 2023 in order to register your birth.
Please also provide any further documentary evidence of your relationship with "Mother" and Father, that you wish to be considered in support of your application.

Reason for the delayed registration was, in Pakistan the main document which is used for all kinds of registration like school registration/passport/smart card etc is called FORM-B also known as CRC (child registration certificate), it's the official document which is issued by NADRA (National database and registration authority), we never needed birth certificate until now (for uk visa) that is why we applied for late registration. CRC has both mother and father name on it, but the problem is, we issued two CRC till today through nadra, one was in 2019 (when i was living at my parent house for some time, address on the CRC is of my parent's address who live in another city), My husband got a new CRC copy in july 2023 and changed address to our present address (This CRC was presented while registring birth certificate).

CRC document is in our local language (Urdu) we can get it translated, but is it a valid document if we attach in the reply?
My son's passport was made when he was 1 year old, but on passport only husband's name is mentioned, on my son's smart card (CNIC) husband's name is mentioned. Because on legal documents only father's name is mentioned.
There has been no situation so far where we had to admit child in hospital or needed to take any medical form, so there's no medical form that has both parents name on it.

I am unable to find any document that has both husband and mother name on it.

Please note that, I already have attached following evidences in child visa supporting docs
1. FRC (Family registration Certificate issued by Nadra)
2. Birth certificate (late registration of child, which they're highlighting)
3. School certificate stating that both parents are registered as guardians in school and pick and drop child.
4. CNIC (Government issued ID Card)
5. Consent Form to send abroad and residential arrangements.



Please suggest, what shall we reply to the email, above mentioned documents were already presented, what supporting documents shall we provide more? and What should be a good reason for late registration.
In short, I need your full guidance and support in this matter. As they've given us few days to reply with answer.
Thanks

Please Note:
I am unable to find any document that has both husband and mother name on it other than those i already attached while applying for visa. Documents i already provided them are.

1. FRC (Family registration Certificate issued by Nadra) both parents name on it.
2. Birth certificate (late registration of child, which they're highlighting) both parents name
3. School certificate stating that both parents are registered as guardians in school and pick and drop child.
4. CNIC (Government issued ID Card) only father name on it
5. Consent Form to send abroad and residential arrangements.(signed by both parents)

There's no official document other than above which have both parents name now except CRC which was used to register birth certificate (this CRC was issued 10 days before late birth registration).

Some people told me to attach Affidavets from different people/relatives.
Also told me to get DNA test performed and attach reports

But I want to know some experienced people what should be our next step.

Your reply seems logical. Hope you submitted the same . Its elaborate and in details. Did you get the visa approved dear?
What all documents you uploaded?