My brother is coming over from Canada in September with his son and my brothers new burd . My brother , my nephew & I are all over 6' , my wife is 5'8" & a bit chunky , my brothers new woman is wee and slender.
I know this has been long winded ,with my brother & I in the front do you guys think the 2 woman & my nephew will fit in the back comfortably for long days out ? Do it now ! Your a long time dead !!

From that description I imagine you will all fit in, but not likely to be that comfortable if driving long distance (or time).  Life is not a dress rehearsal!

Nephew on the roof ?

I just hope your wife doesn't browse this forum!  2014 SE Loire Blue SD4 Auto (MY15)
Gone - 2011 GS Baltic Blue, Retrofit Electric Leather, Side Steps, 19"SC's, Roof Rails, TT Sat Nav Mod, Retrofit Premium Audio, Retro fit 2013 Xenons with DRL & Sig Strip (Clutch at 47k)
Gone - 2007 GS Narvik Black, Privacy Glass, 19" SC's, Side Steps,Roof Rails, Roof Spoiler, Lamp Guards, Retrofit Electric Leather (Clutch at 115k)
Gone - 2007 SE Santorini Black (Clutch at 120k)
BT IID (best money ever spent on a car)

Simple

Let the wife drive, you sit shotgun and let the bros and his misses sit in the rear with the kid

Your able to drink when you end up at the pub through the day and restaurant on way home  Former Mod/Member, with the most post & Chicken George Arch nemesis

I like the way you guys think .. I was thinking of putting the roof box on and letting my brothers burd ride in there.  Do it now ! Your a long time dead !!