And Plunket is offering car seats for both newborn Carter, who is now healthy and doing well, and his older brother, 2-year-old Koen.
"I've been gobsmacked by the generosity shown to us," Ms Weir said at home today.
"We've had so many messages from friends and strangers, saying it's just horrible and good luck for the future. It's just so nice to have so many people be... well, just so nice. I'm quite speechless."
Read more: Stolen car last straw for new dad
Friends of the couple yesterday also set up a Facebook page, Thompson Weir Fundraiser for people to offer donations and messages of support.
Mr Thompson, 31, had just walked out of hospital, having endured the most stressful night of his life where he thought he would lose both his unborn son and beloved partner, when he found his car had been nicked.
He had been on his way to pick Koen up from preschool to meet his new sibling, and see mum Ms Weir, 27.
"Who would do that?" an exasperated Mr Thompson said.
Ms Weir had gone into labour about 8pm on Thursday night.
A midwife suggested they hurry from their home in Hornby, west Christchurch, into hospital.
There were soon complications - the umbilical cord wrapping around unborn Carter's neck.
"Things took a real turn for the worse and I thought I was going to lose them both," Mr Thompson said.
"About 15 doctors came in and they decided to do an immediate c-section. Thank God they're both okay."
The pre-cast concrete worker praised the quick and professional actions of the medical team.
When Canterbury Plunket area manager, Anne Feld saw their story, she immediately wanted to lend some support.
"Adjusting to a new baby is hard enough without the added stress of something like this," she said.
"Plunket is fortunate to have a wonderful family of sponsors so we asked them to come to the party. Plunket partner Miles Toyota are providing the family with a Rav4 for a month or so until the family get back on their feet.
"Plunket's Car Seat Service has a fund to help families in situations like this so we will also be providing them with two seats to help them through this time as well as knitted baby clothes."
The young couple, planning to marry later this year, said the support has been "absolutely phenomenal".
"Our faith in humanity has been restored. It's been really humbling," Ms Weir said.
"When we saw Nathan and Shannon's story in the New Zealand Herald, it really connected with our team on a personal level,'' said Alistair Hazeldine, dealer principal for Cockram Nissan.
"Any Christchurch business should feel a sense of responsibility when it comes to supporting our local Christchurch residents, and here was a sad story about a young couple being kicked while they were down.
"We discussed putting together a care package of baby gear but in the end decided to simply present the couple with a cheque and the opportunity to spend the money as they see fit.''