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Getting 16 kids together isn't easy, especially when they're now living around the world and one is expecting her third set of twins.
But after countless emails and phone calls, the Assen siblings are gathering this weekend in Hamilton to celebrate their parents' 40th wedding anniversary. It is the first time in 14 years the family has been together.
"It's exciting," father Bert, 64, said. "The kids did most of it. I just said, yes, yes, yes."
The large Catholic family first featured in the Herald 19 years ago, after the youngest child, Catherine, was born. Now studying tourism and marketing in Sydney, Catherine said the family had been talking about the reunion for four years, but did not think they could all make it until recently.
Catherine arrived on Monday, while the last of the nine sisters and seven brothers were due to arrive from places as far away as Chile and Canada last night.
The family has grown substantially since their last gathering, with the siblings - ranging in age from 19 to 39 - now having 21 children between them.
Eight of those belong to Diane, 37, who already has two sets of twins and two more babies due in June. Her maternal grandmother also had three sets of twins (her mother, Lida, 62, is part of the youngest set), and she has twin sisters, Corina and Linda, 38.
The reunion will begin with a mass at the family's parish church, St Pius X in Melville, at 11am today, followed by a lunch for 160 at the Glenview Club.
Dinner and another lunch tomorrow will be "just the kids", although that includes their partners and children.
Mr Assen, a farmer, said he and his wife had always wanted lots of children. "When we got married, we hoped we would get a decent family," he said. "Lida thought six and I thought nine. They just kept coming."
Catherine said the most common reaction to the size of her family was disbelief. "As soon as people hear it, they're like 'What?!' But I love it. I wouldn't have it any other way ..."
She said growing up in such a large family had taught her to share, particularly as there was only one bathroom and toilet in their house.
The Assen siblings are Robert, 39; twins Corina and Linda, 38; Diane, 37; David, 35; Paula, 34; Terry, 32; Teresa, 31; Peter, 30; Bernadette, 28; Michael, 25; Maria, 24; John, 22; Joanne, 21; Joseph, 19; and Catherine, 19.