I understand your situation, because your hubby got the british citizenship by descent, so if his child born oversea (not UK), the child can not inherit the british citizenship.
If you and your hubby is moving back to UK in few years time. If I were you, I will give birth in HK, so the baby will have HKID and HKSAR passport, and Chinese Home Return Permit.
When the whole family moving back to UK in few years time, I guess your hubby can apply you and the child in one application form for family migration. (just guessing coz I am not living in UK).
Birth 15/3: W:4.2kg L:52cm HC:37.5cm
Day 09: W:4.37kg L:55.5cm HC:37cm
Day 46: W:7kg L:62m HC40.5cm
Day 82: W:~9.2kg L:~66cm
Day 112: W:~10.4kg