求助:想把宝宝抱回国,都需要什么手续

宝宝快8个月了,但是我和老公目前都无法把宝宝留在身边,所以只能让宝宝的爷爷和奶奶带回国一段时间。
现在我想问问由爷爷奶奶带回国,都需要些什么手续??怎样证明爷爷奶奶和宝宝之前的亲属关系呢??
先说明,我宝宝已经是英籍了。
还有,如果想给宝宝在国内办理寄养签证的话,都需要什么手续呢??
我在这边网上实在找不到太多的信息,希望有经验和了解的朋友们能助助我
谢谢了~~

My experience of " 爷爷奶奶带宝宝回英国入关" i’m not sure if it will be the same to bring baby back to China.

Sample of:

Letter of Authorization for Travel

(Date)
I (parent’s name), authorize my child/children, (child/children’s name) to travel to (destination) on (date of travel) aboard Airline/Flight # (flight information) with (accompanying adults), returning on (date of return).

Signed by Parent or Parents
Name:
Address:
Telephone/Contact:

亲,你太伟大了~~谢谢你。
请问还需要带什么手续吗??像宝宝的出生证,或是爷爷跟爸爸之间的亲戚关系证明吗???
还有请问你知道怎么公证宝宝的出生证吗???

my baby’s have got Chinese HUKOU and his HUKOU is in the same book of 爷爷奶奶. so i also bring the English translation copy of their HUKOU. (this is just in case) 爷爷奶奶don’t know English so when they get to the passport control they just give the officer everything i prepared.

my baby’s Nortary Public of the child birth certificate was done in China. the office is call “涉外婚姻办”