Well that's what I want to find out. He didn't inherit the castle: it was the seat of the McNaughtons until around 1689 when it came into the hands of Campbell of Arkinglas. There's a great deal on the net about how the Campbells "tricked" the MacNaughtons into losing their lands and castle, including a wonderful story of the MacNaughton Laird wanting to marry a Campbell lass, but tricked into marrying an older sister. The story goes that he then ran away with the younger sister and set up a new seat in Ireland. It's more likely the lands and castle were confiscated and handed to the Campbells, but it's a great story.
What's harder to find is information about who lived at Dunderave in that period after it was acquired, which is when my Patrick was growing up. Presumably some Campbells were installed there to run the place and Patrick must have been one of them. He's mentioned in Burke's Landed Gentry as "of Dunderave" , which suggests he was "gentry". He had 15 children by two wives!! His daughter Beatrix married a James Murdoch Esquire and they called their son James Campbell Murdoch. The tradition of giving a son the name Campbell went on for six generations and survived migration to Australia. I was taught to think of myself as a Scot of Clan Campbell! You can take the people out of Scotland but you can't take Scotland out of the people.
It's giving me such a thrill to find out where it all started. Very grateful for people giving up their time to help.