They both have young children and they live in Melbourne, which this year means they have been effectively housebound and, on top of that, home-schooling.

That's what makes their take on children's music so unique. It's not irritating. It's not inane (no baby shark doing the "do do do" here). Instead, it is educational, funny and easy on the parental ear.

The sisters formed Teeny Tiny Stevies as a sideline gig for their indie folk-pop band The Little Stevies. The idea was to create music which encouraged conversation between adults and children. Messages shared are packed with emotion, clarity and humour - a prime example being the messy-house anthem Family Is A Team.

The sisters had no idea their hobby would become their career but their harmonies, melodies and catchy choruses struck a chord, and the 2018 ARIA-nominated Helpful Songs for Little People became a word-of-mouth sensation among parents. Their colourful animated videos (by long-time collaborator Simon Howe) have clocked up hundreds of thousands of views online, and more than 10 million views on ABC iView.

Byll Stephens is happily perplexed at the success of Teeny Tiny Stevies to date.

"Someone referred to me as a 'kids' performer' the other day and I had this really weird reaction," she says.

"I totally understood where they were coming from, of course, and I totally understood why they would say that to me, but I don't put myself in that category in my head.

"I love watching the kids having fun and then being able to throw a joke at the parents and watching them laugh."

Their songs are written about everyday topics faced by parents and children. Useful Songs for Little People (2015) contains songs like On The Toilet, You'll Have To Be Patient and Getting Dressed. Helpful Songs for Little People (2018) includes Boss Of My Own Body, Pass The Sunscreen, No Peanuts, Quiet Time and Sleep Through The Night.

As for Thoughtful Songs For Little People (2020), think Had You To Teach Me, Plastic, Happy Swimming and Respect My Pet.

You get the idea.

Song Good For Your Health was released as a single earlier this year, Stephens says, because parents "kept tagging us online about hand washing".

"All the themes for the song on the current album were crowd sourced," she says.

"We asked parents on social media what challenges they were coming up against, and what they wanted us to write and sing about. Personal hygiene was high on the list so we wrote Good For Your Health. We wrote Stay At Home during the first lockdown. It's not on the album, it's completely new."

The lyrics could teach many adults a thing or two.

"You must be sick of being told, To wash your hands and blow your nose, And cough into your elbow, Boring stuff that we all know, But right now that's our best defence, Our barricade while a cure's in progress, So when you do these little things, You're actually making a big difference."

And then there's Superpower, a song about emotional intelligence which encourages children to be resilient: "The power I yield is hard to see, It's a secret agent who shows up when I need, Means I can stay in charge of how I feel, It's a power that lives inside of me."

Says Stephens: "Our intention when making this music is with repeated listens in mind and look, if you listen to anything 50 million times it can get annoying, no matter what it is. We get that.

"But music has a way of stamping something on your brain - I still remember the Pizza Hut phone number from the jingle in the '80s - so we decided that if we were going to stamp something on people's brains, if we were lucky enough to get to do that, then let's make it's sensible, useful and inclusive."

Without sounding preachy?

"Oh gosh, we're not parenting experts and we couldn't be preachy even if we wanted to be," she says.

"We just make songs interesting for parents as well because they're going to be listening to it over and over again. Parenting is so hard, for me anyway, that maybe I'm writing these songs for myself [laughs]."

Teeny Tiny Stevies' first national tour sold out in a matter of days, and their second - which was to conclude with a performance at the Sydney Opera House - was cancelled due to coronavirus.

They are looking forward to performing for families, live, again soon.