Registering at Police Station - can this be done at airport

Hello
My daughter and I (one on NZ passport and other on UK passport) are travelling NZ > Shanghai > UK in July.
We will be staying for 48 hours in total.
My questions are:

1. How exactly do we organise the transit permit in advance? If we do not tell the airline, can we organise it when we get there?

2. We are staying with friends in Shanghai, not at an hotel. Can we register our permits at the airport or do we need to go elsewhere?

Thanks for your help