I actually agree with Katie on this one. It's not always possible to have a birthday party on the exact day. She clearly loves her kids very much, but just gives them a party on the weekend where it can be celebrated as a family, together.
The other woman came across as a bit hypocritical to me. Going on about how children's birthday's should be celebrated on the day, when actually, she did send one away to boarding school and I bet she hasn't seen them on their birthday.
Or maybe she sees them on their birthday and not the other 364 days of the year!