Just curious - why did you think you were going to have to sell the car? Financial reasons? I'm assuming so, because I'm sure the RS4 is capable of carrying two adults and two children?!
Nope not financial reasons. The RS4's boot spaced is deceptively small and with two car seats in the back the middle 'seat' was gone so that load space was compromised. Believe it or not the load area (depth and width, not height) in the RS4 is much smaller than a Golf R estate(!). We were fine with one child and the dog, but the problem we (she's now my ex) had was our dog Betty travelled with us in the boot when travelling across the country to stay with our respective families, and also when we went on holiday...
(pic taken pre second child)

Two children on their own would have been fine, but two children AND the dog, the buggy, and all the paraphernalia that went with two small kids was a problem. The roof box was used for the buggy and some bags (not the dog!), but it eventually became a logistical nightmare and no matter how much I tried to justify it the RS4 was simply too small (even with the roof box) so I sold it for a new Range Rover Sport, which fitted us all in easily and then some.
