Thank you.
My main concern is that I have picked Montreal, QC as my intended location to live when I filled my application. Because of that, I have received extra certificate from Quebec (CSQ) as a proof that QC agreed with my application too. I was confused if we need similar certificate or extra process from BC in case we move and I was suspicious if it can cause extra delay. We are not sure about this move yet but we will decide soon. My partner is still in negotiation with her future employer.
I'm sure QC has a different process than the other provinces, most of their laws are. I would consult with a Canadian immigration attorney or consultant regarding the certification issue. Are you currently in QC? I think the purpose behind wanting to confirm your intentions of living in QC may be that a) they likely have a different immigration process then the rest of the country, and b) they do not want to review cases from across Canada, only those that affect their province, to ensure that your application went to the intended location you wish to reside in.
Having said that, I also believe they are aware of people's ability and choice to move within the country. This is with the assumption that you or your partner is a Canadian citizen and not PR holder applying to sponsor family.
I would consult with an immigration attorney or consultant for more information. Or look online, like possible FAQs?
I just know that they need to be informed on significant changes, address is one.
And the more I think about it, the more I think that the move might cause delay in process because your file would need to be transferred to a local office to your new location, and if QC does things differently, they may want to get additional information from you, and you might either be on a new time-line for how your case gets handled, vs being placed in the same position in the new province as if you had applied there to begin with. In other words, if applied in Sept 2018 in QC, BC accepts that as your date with them too and places you with the Sept group, as opposed to your case being sent in June 2019, and BC accepts it with the June 2019 bunch. (All assumptions btw).
Good luck!