"No, we aren't," Lily corrected because she hadn't invited Sirius out and she saw no reason to continue the charade and make the poor waiter think to expect someone else tonight. She did flash Remus a little look because she didn't think this was usual for him, but ... well, it was strange times. "I didn't invite him," she said to Remus in case he was somehow actually under the impression Sirius had been invited and was late.
Nothing about this entire situation rubbed her the right way, and it all felt drastically sneaky and underhanded, and that wasn't how she operated at all. Still, she'd at least see what this was all about before making any sorts of judgements.
She smiled to both Remus and the waiter. "If we could have a moment to look over the menus?" She suggested; she didn't know what they had so how could she decide what she wanted?