Sending my child to India with grandparent

[SKJMR]

Hi,

I am planning to send my 18 months old kid with her grandmother to India via "AIR INDIA" flight

1. my child holds British passport and also Indian OCI card
2. grandmother Indian passport holder
3. both got different surname
4. flight airline- AIR India, in which they will be travelling in

5. i am sending both parents myself/wife British passport, OCI photocopy myself/wife, child UK birth certificate,
child has British passport and OCI
6. consent letter , signed by both parents

what more documents do i need.
I rang AIR India, they said i need to contact nearest Indian embassy, i have been ringing embassy in Birmingham, but nobody is answering the calls

my question,
1. can i send my daughter with my mother in law ?
2. if yes, all the above documents enough or not
3. if no, what else should i send
4. do i need to contact Indian embassy
5. anybody recently been in the same situation?

Many thanks

skjmr