Dd2 is 7.
The niece and the friend are 13 and 14.
They want to take her to the cinema in town. They'll get a lift there and walk/get the bus back. It would be during the day, so not dark.
The bus stop/route they'd be walking is along a dual carriageway.
He's done this before, I've told him that dd2 is too young. He did not listen and has planned it again. I've told him if it is going ahead I'll have no choice but to stop dd2 from staying with him.
So as not to drip feed, dd2 has a habit of running away when she's in a mood and has zero road sense.
She reduced my mother to tears a few weeks ago owing to running in the road when it was icy, refusing to listen and refusing to hold hands (whenever my mum made a grab for her hand she bolted and my mum couldn't run as fast in the ice)