How long have Focus Group and Neighbour Group people been in contact overall?

Since migration from the Salish Sea region until recently. This migration may have begun around one millennium BP.

What is the overall time frame when the largest number of people had the most opportunities for interaction?

From the time the Nuxalk established settlements in and around Bella Coola until recently.

How long have Focus Group and Neighbour Group people practised exchange for?

Around one millennium

What is the time frame when the largest number of people had the most opportunities for interaction in exchange?

From late 18th century until present

How long have Focus Group and Neighbour Group peoples been forming families with each other for?

Possibly as long as they have had general interactions (see earlier comments)

What’s the time frame of densest contact between Focus Group and Neighbour Group as far as family formation is concerned?

Same as the time frame pertaining to general contact suggested earlier

What is the time frame when the largest number of people had the most opportunities for interaction in trade?

Late 18th century until recently