Bellatrix was surprised, but she supposed love could do that to a person - make them more accepting. If, indeed, Lucius was truly in love with her sister, or at least infatuated with her. Only time would tell how much he really wanted to invest in a life with Narcissa.
"It does sound lovely," she agreed. "Shall I let you run along to him now, then? I am sure he will want to hear the good news."
[ooc: I think this thread is nearing a good stop unless you have other ideas. I think it'd be a lot of fun to act out the party & its preparation in another thread, though!]