You have to have a guide unless you have family that is the first degree of kinship ie. mother, father, sister, brother. etc. They also have to of had a hunting license 3 of the last 5 years and they have to hunt with you. My wife is Canadian and from BC. She lives here but the rest of her family lives in BC. Her step dad has started to hunt again so I'm getting closer to being able to go.
Yes, guides are mandatory for non-residents unless relatives are involved. Pretty hard to come up with the change for a guided Stone hunt. I hunted in Northern BC for 3 years in a row for Moose, or I should say I had a Moose tag in my pocket. It was a new area for the outfitter full of Elk which he had never hunted before. I ended up spending all my time guiding for Elk and he kept telling me to come back for free the next year. The 4th year he asked me what I wanted to hunt. I said Stone Sheep and the rest is history. Cost me the price of the tag. I'm still waiting on my Bighorn after putting in for 40 years in Oregon.
Regardless if you have family in B.C. there is no hunting for sheep or grizzly without a guide. We have a hunter-host program in B.C. and it stipulates that when you make the application sheep and grizzly are not allowed. Ramshot