In the manga series (volume 10 if I'm not wrong), Yukito said to Touya that all of his memories about his grandparents are all false. When watching the Illusion capture episode, I got an idea that Yue changed Sakura's clothes using magic (just like other animes whose characters could change clothes using magic).
About Sonomi... (spoilers warning)
I guess she liked Fujitaka. Every time she remember about how Fujitaka married with her beloved Nadeshiko she became angry ^^. And remember the episode when Sakura came to Tomoyo's house for the first time, Sonomi said that Fujitaka's only mistake is that he has no mistake. Aren't these signs that she like Fujitaka?
No, it's a sign that she doesn't really loathe Fujitaka as she says she does. In volume 2, she says that Nadeshiko was the happiest when she was with him, so she obviously appreciates the fact that he made her truly happy.
She gets angry when she remembers the two of them all lovey-dovey because
she loves Nadeshiko. In the same way that Fujitaka loved Nadeshiko.
And btw, I've always been amused by the changingclothes!scene. Yukito does say his grandmother changed Sakura's clothes, but later on he also says he has no grandparents- his memories of him and all were just an illusion created by Yue (or Clow?) so he'd be a good disguise. So you gotta wonder how the HECK did Sakura get her clothes changed XD
