Retirement Visa In NZ - UK Daughter, NZ Son in Law

Hi Everyone

This is a real long shot so hoping someone might be able to help me out.

I am a UK citizen living in the UK with my husband who is a New Zealander, he has ILR but looking to graduate to citizenship this year. My question is this, once he has been granted citizenship, we plan to emigrate to New Zealand. My parents are also UK citizens and would like to emigrate with us. They are both 70 years old and are retired. I have seen that they can apply for a tier two retirement visa (unfortunately they do not have the funds to qualify for tier one). I am an only child so means that I am their only living relative which I believe is a condition of being granted a tier two retirement visa.

As both parents are 70 we would like to make the move sooner rather than later, does anyone know if we can all apply together from the UK using my husband as a sponsor? He would travel to New Zealand and secure a job before we made the move. Or would myself and my husband have to emigrate first and my parents follow? Once all in NZ my husband and I plan to buy a house for them to live in, they would sell their house here in the UK and live off of the proceeds.

Wonder if anyone else has had any experience of this?