The Mountain buggy can have one side adapted with a car seat clip. However having spoken to a Red Cross lady at a course recently I will be decanting any future babies into the pram rather than leaving them in the car seat.
Scary stuff about little heads falling forwards and cutting off air supply. There was another lady there who had a premmie baby and she was not allowed to take her home until they had tested that her baby was getting enough oxygen for 40 minutes in the car seat(twice time taken to get home). Anyway this thread isn't supposed to be about this...so I will stop. Sorry boohbar.
I saw a super-expensive one last year that I really wanted but when I saw it in a shop it was massive, really really wide and would never fit through a shop doorway. I think it Bebecar and it could do car seat and carrycot attachments as well. Very nice though! I'm sure bebecar have a website so you could probably find it there.
Yes! I have one: Graco Duo Tandem Travel System. It cost me £170 2.5 yrs ago from a now defunct website, including the carseat bit, but hopefully you can find it somewhere online. I see them about. American family have described it as "SUV buggy", English friends are more succinct simply saying "your posh buggy" -- it's a heavy long tandem, but good choice for people who do much walking like I do.