@Geezer
Perhaps - I use the word "visa" for any stickers from Exit/Entry inserted into our passports - and I've never really learned the official english name of the local PSB residence paper thing...so I usually flub and mutter some words, followed by "local psb piece of paper thing"...

But yeah - until I exited and re-entered China - I carried BOTH passports because of the Entry Stamp thing.

If memory serves. With your household registration, from your district police station, your registration is linked to your passport number.

I don't think you need to change this, but after you have exited, and re-entered the mainland you (as per normal) need to re-register you household registration. I needed to take both passports when I did this the first time of using the new passport.

If you renew your passport or the passports of dependents - PSB must be notified in a timely and prompt manner.