Help with travel to, and within, Canada please

[BIWI]

Planning on a trip to see family next summer, in New Brunswick.

I have loads of BA Avios points, so would prefer to use those - so we could fly to Boston/New York and then travel on to Canada, or into Canada to Toronto or Montreal.

Nearest airport to family is St John, in New Brunswick, but there are few flights into there. We could fly into Halifax, Nova Scotia, where there are more flights, and family member(s) will happily come to pick us up.

But internal flights seem to be ridiculously expensive! Rail routes are limited too.

I'd rather not hire a car, as those are long distances (and we're not planning on being there for longer than a fortnight), so I'm a bit unsure how best to proceed.

Any Canadians (where is StewieGriffinsMom?!) here who can give me some pointers or inspiration? I'm a bit internet-searched-out right now.

Not Canadian, but have travelled on the Eastern seaboard. We were supposed to fly direct in and out of Halifax, but Air Canada grounded the Max planes.
Our re annranged journeys via Toronto and Quebec were long and torturous.
If you can fly direct to Halifax and get your relatives to pick you up.