回复：出生证明一定得两次公证：先去MILTON KENEYS的英国公证中心做

not necessary to do 公证, original birth certificate is enough, you can do translate in local translation company in China, it is enough to do 户口 in security office in China.

I did apply 户口 for my second child, no problem, also don't need pay panety for second one if you go aboard for more than 1 year. China has such policy to welcome professional come back to China.