spiker, I think Ursula has visited twice. Once was an unexpected visit at quite an early stage, when she didn't even seem to know that they were engaged, and Knob did seem pretty pissed off about that. It was shortly after that that Helen arranged the big family dinner that Knob's parents didn't turn up to, because he never invited them, and he generally went on about how typical it was of them to be so rude, how they didn't care about him and what an awful family he had generally.
Then Ursula visited again quite recently, after Helen got pregnant. ISTR Knob was still quite wary but more receptive, maybe because he felt one up having conceived precious first grandchild. She came over as probably just as controlling as Knob, so they will probably be kindred spirits.
It would be nice to think that if she's going to be hanging over Helen all week, Helen might get round to saying what a shame it was they didn't make it to the dinner that wasn't and Ursula will say she wasn't invited. But Knob will probably tell Helen it was all her fault, she was the one who was supposed to organise the invitation, and do that horrible laugh while he points out that she was a confused little woman even before she got pregnant.