The party this year is to celebrate the wedding of the Jones', which happened in January in Rarotonga.
But it could also see the start of another courtship: that of National trying to woo NZ First.
It is understood that after initially declining the invitation, about 12 National MPs will now be going, led by Steven Joyce.
NZ First leader Winston Peters will also be there.
National MPs have always attended in different numbers - the first year it was just Mark Mitchell and Alfred Ngaro but since then Joyce and others have attended.
This year was almost a no-show but there is concern among some National MPs about closing NZ First out. So the party could well mark a decision of trying to restore some amicability to the relationship lest 2020 be a repeat of 2017 - and NZ First has the balance of power.
So diverse is Jones' field of friends that his party is like the watering hole in the desert - a morass of people who are natural enemies gather there to drink. They include politicians, business people, media and family. They include fisheries interests and environmentalists... oh hang on.
Such is the antipathy NZ First has to the government support partner, the Greens, while all the National MPs who will be in town were invited the only Green Party MP to get an invite was the leader James Shaw.
Although it is an invite only party, it doesn't stop gatecrashers and so Shaw is expected to have some company in the form of Julie Anne Genter.
As for Ardern she will have a day off up North before the formal ceremonies for Waitangi begin tomorrow. Her day at the peaceful marae in the Karetu valley will have gone some way to restoring the faith of politicians in the hospitality of the north after the often bitter taste powhiri at Te Tii Marae might have left.
Ardern was gifted some pounamu and the marae took line honours as the first not to gift her a baby name although there was a joke "now with those taonga goes naming rights."
Ardern also likely learned that among Maoridom in the North there is no such thing as a secret. The event at the marae was intended to be a surprise for Davis. Even media were cautioned to be careful not to mention it to him.
He drily observed that it was indeed "as much of a surprise as an open invitation on Facebook can be".
In the end the only person who got a surprise was Ardern's partner Clarke Gayford who had presumed his official duties were over after the powhiri and gone awol. Then his name was called out to receive a taonga during the presentations, necessitating a quick sprint back into the meeting house, tearing his shoes off as he went to the soundtrack of the crowd laughing and clapping.
