Sirius & Remus & James.
Sirius didn't fuss about them escaping from him and instead circled the sleigh himself, eyeballing it for ideas of how they could make it fly. He left getting a sense for the wood up to Moony; he was the one who had the affinity for shaping wood.
At Remus's question, Sirius shook his head, a grim set to his mouth as he did what he and James often did, speaking on the other's behalf. "Not for big magics. I was thinking it handling issues, but the longer we go on I reckon it's that what the wand wants to do is diametrically opposed to what either of us wants to do with it."
Without comment, he handed his own wand over to James so he could cast all the charms he wanted to the standard to which he was accustomed. Then Sirius climbed up into the sleigh and looked up at the sky, so dark and clear above them. "I think Moony's right and we won't find ourselves, but I'd still like a look at it. I'd be interested to see how the Big Man quantifies naughty and nice."