People have found out on other sites who that mystery brunette is.
Apparently it's a model called Shafia West and she is in her early thirties (aged 30-33).
She follows Joshua on IG and he follows her too.
Here is her IG account:
https://www.instagram.com/shafiawest/?hl=en
i guess she visited Josh when he was doing his play in Berkshires in June.
@shafiawest
The Berkshires
https://www.instagram.com/p/BVirV4CA...-by=shafiawest
I think she is very pretty and cute. And also i not suprised it's a model. Josh and his brother love models. Most men do actually.
UPDATE: IT IS SHAFIA WEST!
She was indeed seen attending Josh play in Berkshires. And they seemed happy together.