Am I looking for the impossible?

Silversands I had this problem years ago when we had 3 under 4yrs and went into Halfords for their advice and also Mothercare/ToysR.Us they where very helpful but I just can't remember what I bought as it was such a long time ago to be truthful I did have a larger car than a Fiesta so maybe I bought a standard size but it would be wothwhile enquiring.Also you could still have one in the front and two in back but I'm not sure what the regulations are nowadays.

Thank you for that reply. Unfortunately I went into Halfords and as soon as I mentioned three grandchildren the assistant took a sharp intake of breath and said "You are asking the impossible" never even offered to try any of the seats in my car, suggested I buy a bigger car and come back in to discuss it. I said "There must be one make of car seat that is narrower than others", assistant said "Well if you find it come back in and tell me about it!"

ToysRus had a very limited number without Isofix (which I didn't want) so tried one make, which I would have bought but they fitted it in such a way that there was a good 3" of space at each outside edge of the actual back seat thus reducing the space in the middle to about 6" therefore assistant said "Oh you wont get a booster to fit into that small space". I know when I fitted the back facing baby car seats I had about 1" either end of the back seat and about 13" in the middle more than ample to fit a full size booster seat. I don't know how to resolve this problem, but I am sure I cant be the only Gran or parent with this problem

I have a large 6-year-old GS who is allowed to sit in the front of his parents' cars, using a booster. I hope this is legal.

I'm not sure how you would manage the seat-belt problem - there will only be two fitted in the back, surely?

No I have three full seat belts, as I say I didn't have any problems with the back facing baby car seats plus booster cushion fitted in the centre between them. I read about the Bubble Bum, any used one of those?

Silversands have you thought of asking on Mumsnet they do seem to have all the answers and someone will have been sure to have tried the Bubble Bum and give their opinion. Well worth a try.

We had a Bubble Bum so that we could get a three year old, his Mum and new baby in her seat all in the back of our car. It worked fine but we only used it a few times then they all emigrated to USA. I got it from Amazon.

I thought Mum`s net were having a website issue right now?