DD1 (just turned 6, pretty tall for her age) is due to go to an after-school activity tomorrow. It's her first time at this activity. I'm at lectures until late so a friend has offered to drive DD there and back. I'm hugely appreciative as it gets us out of the complication of after-school care & also means DD can do her activity with her friend.
Today friend's Mum came to collect booster seat for tomorrow. Just got a message to say it doesn't fit in her car with other car seats. 
Only options I can see are no car seat, or DD in her booster in the front. It's about a 20 minute journey. I've had her in the front with booster seat for short journeys before, but would two 20 minute journeys like that be just too much of a risk? It's mainly suburban roads with about 10 minutes on (not crazily busy) motorway.
And if I am BU, does anyone have a possible solution that I might not have thought of?