Molly had watched their reactions very very closely. It wasn't that she wanted them married, she just wanted to make sure that Bill had a future with this girl. That moving in with her was a good idea, and not just something the two of them had cooked up because they were randy.
Neither of them gave her much to go on, but at least they weren't completely denying the idea. Molly wasn't quite sure what to think about that actually.
"Right" She said immediately after Bill had stated his desire for pie. On another day, she would have laughed, she would tell her grandchildren this story one day. "I'll just get you the plates." She waved her wand and two plates floated out from a cupboard, "And get going. I'll see you Sunday."
She turned to leave, "Oh! I forgot to let Ginny and Ron know you're coming. Arthur's delighted to see you of course." She directed her parting words to Fleur, and with a quick wave, she disappeared into thin air.