The closest they get is a basic arrangement of when they'll drop a song in, and what that song will be.
"Yeah we know what songs are coming but everything else? - no idea - it's different audiences and different reactions and we just love bringing the crowds along with us."
And that's about it, for this unique duo of Kiwi comedy and music just get out there and basically play it by ear.
And it works - the list of awards and hit reviews through the years, not to mention the sound of unrestrained audience laughter, underlines that.
"Yeah we've been doing this a while," was how Jools simply put it, adding there were no plans to put the feet up.
She figured when the time came they'd probably extend their character list to include a couple of well matured old folk . . . be something like a "wheels and walkers" tour.
To say they've covered a few miles around the country through the years is like saying they kind of like a singalong and the occasional yodel.
The eight-centre tour they are embarking on is a continuation of three previous tours to as many smaller towns and centres as they can manage.
It is the "Heading For The Hills" tour and features an usual "prop".
A small shed on wheels with a couple of beds in it and a pot belly stove and like its predecessors going back in Kiwi history it is called a "Stinky".
"Lynda came across it," Jools said, adding that the full-scale vehicles were very much a reality back in the olden days when road workers used them as mobile accommodation.
They slept in them, cooked in them and ate in them . . . but rarely washed their clobber along the way, so these rolling bed/trucks accordingly came to be known as "Stinkies".
All part of what the twins love to embrace and that is the unique nostalgia of their Kiwi homeland.
The characters they adopt are cheerfully familiar to many Kiwis and, basically, remind us of someone or something that happened from a much simpler past.
"There was a time when, yes, things were simple and so, yes, our characters are very simple . . . they're good-hearted Kiwis.
Camp Mother and Camp Leader will emerge, as will Ken and Ken and probably Raylene and Brenda but the Gingham Sisters had "hung up their pinnies for now", Jools said, although Mavis and Nora would take time off away from the bowling green and the kitchen baking to make an appearance.
The way Jools puts it is "we just keep reinventing the twins".
They are looking forward to returning to Napier where they have appeared many times.
"Always had good show there and we love the nostalgia - you have that wonderful Art Deco which is a real embracement of the past."
Jools said her brother was great fan of it all and would jump in "his old car" and head for the big Deco weekend celebrations.
They recently wrapped up a couple of children's shows in Auckland to help celebrate the release of their sixth kids' CD book titled Old MacDonald Had a Farm so they put on the shows to sing to the youngsters, which they love, because seeing and hearing young faces smiling and singing is very, very special.
"When we were growing up there was always a singalong going on - and you know the only time we were mobbed was at a play school we went along to," Jools added with a laugh.
They have sung and played since they were just five, and Jools remembered seeing the Chicks (Sue and Judy Donaldson) performing at the Waikato A&P Show during the 1960s and said for a youngster looking on it was "amazing".
"And they were two sisters so we thought hey, that's pretty cool."
But it took a while to get to the stage themselves.
"We were too busy on the farm milking cows then."
● Topp Twins Heading For the Hills, Napier Municipal Theatre, Saturday, October 14, two-hour show begins at 7.30pm.
