My 4yo does tend to try to blame someone else if there's a toy broken or something similar, but she does it knowing I know she's fibbing (no Mum, wasn't me, it was Angus - who hasn't been here for six months). I don't know if that makes sense, but she's just being a bit cheeky when she does it, more than anything. She *knows* I won't buy it. I brush it off and don't make a big deal of it, usually a bit of a joke and then reinforce the behaviour I want (you know you should take better care of your toys and next time, please bring it to me if it happens).

I think it's perfectly normal for kids to avoid getting in trouble for something they know they shouldn't have done. My DD told her first fib before she was two! I had to make a quick exit to laugh. It's less funny as they get older, I'll give you.