The international search is ramping up for the 32-year-old from the Whitsundays, whose two-year-old daughter Adelynn was found abandoned in a local church in Cancun.

The toddler was found shoeless and without either of her parents, but was reunited with her family in Mexico today.

The little girl has also been issued an emergency Australian passport.

Ms Shanks' brother, Daniel Shanks, said yesterday the family has no confidence they will find the missing mother.

"We're doing our best to keep it together but it's pretty tough at the moment," he said.

"I've got no confidence in finding Tahnee to be honest."

The Shanks family is offering a $5000 reward for anyone with information about her whereabouts.

The family tonight released a statement confirming Adelynn had reunited with her uncle and grandmother and thanking "kind and generous people from all over the world" for their support.

"Our immediate goal is to get Addy, her uncle and grandmother home safely as soon as possible. With several hurdles and red tape this may take some time," the statement said.

"We remain deeply concerned for the safety and whereabouts of Adelynn's mother Tahnee."

Ms Shanks had been living in Mexico with her partner and Adelynn's father, Jorge Aguirre Estudillo, and was holidaying in the country's south when she disappeared.

Her brother confirmed the relationship between his sister and Estudillo had begun to deteriorate, with Shanks considering a return to Australia.

Witnesses say they believe it was Estudillo who left the young child at the church.

"We've got three eyewitnesses telling us that, verifying it was him. And Tahnee's the one missing," Mr Shanks said.

"And he's on the run, as far as we're concerned."

Mr Shanks said he was initially contacted by his sister's concerned ex-boyfriend after the young mum went silent on social media.

She has not been heard from since Sunday.

Mexican police have obtained CCTV of the car the family was using leaving their residence.

"We do know they've gone to Tahnee's residence ... gone inside and searched the place, got CCTV footage of the vehicle leaving," Mr Shanks said.

He added the car the family had been driving was recently found dumped in Cancun, two hours from their travel destination in Tulum.

Estudillo is wanted for questioning but has not been located by authorities.

Mexican authorities have filed a missing persons report while police in Australia confirmed they are doing what they can.

"If it involves someone who should be in Queensland, or was meant to be coming back, we will be involved in that to find out what's gone on and get answers for that family," Queensland Police Commissioner Katarina Carroll said.