I have some non tethered seats we have bought for different reasons and only use them on certain occasions. I would prefer to use them, then risk no seat at all (even before it was illegal to have a child under 7 not in a seat).

My belief is that they have to fit a particular standard here in Australia, so they aren't all bad, however both my kids comment on them being not comfy.

I have 2 infa secure at my mum's. I bought them on our last visit, as I needed 2 slimline seats as we had to squeeze an older child in the back as well. I also have a safe and sound one that my cousin leaves in her car for ds.

If I can, and the trip is planned, I will take the seats from one if our cars (we have anchored seats in 3 cars permanently as my dad lives with us and helps out with school run) and put in another friend/family members car.