adding a new line

Hi, I just moved to BC from Ontario. I want a local number for my business here, but I still want people to be able to contact me with my old phone number. What is the best way to accomplish this? Do i have to add another line? And use 2 sim cards with the same phone? If that’s the case, i would like to get a very basic plan for the new line, but how do I set it so that the data and my personal things are always on my original plan, and the texting and calls for business are on the business line.