Sharna Burgess shares photo of new baby and partner Brian Austin Green's sons with Megan Fox

Aussie dancer Sharna Burgess has shared a rare photo of her and partner Brian Austin Green's baby and his three sons with Megan Fox.

Burgess took to her Instagram account yesterday to post a video of their blended family to mark three months since she welcomed her first child with the former Beverly Hills 90210 star.

A photo at the start of the video montage features baby Zane with the three boys Austin Green shares with his ex-wife, Fox.

Watch the video above.

READ MORE: Meet the grandmother who will give birth to her son's baby: 'So eternally grateful'

"Three months of you," Burgess captioned the sweet post. "Three months of watching you grow, of being in awe of you and of experiencing a love like I've never known.

"Motherhood is by far the coolest thing I've ever done and I'm so grateful for all of it. The magic, the love, the fear, the sleepless nights and the memories of it all. I am the luckiest Mama in all the land."

The video captured tender moments from the past three months, including the minutes straight after Zane's birth, Burgess breastfeeding her son and leading him through baby exercises, floating in a swimming pool, his first smiles and sharing giggles with his dad.

Burgess, 37, and Austin Green, 49, welcomed little Zane into the world on June 28, and the couple wasted no time introducing him to his half-brothers and even Fox herself.

READ MORE: 'Creepy': Coco Austin slammed for bathing six-year-old in kitchen sink

During an appearance on Good Morning America last month, Burgess, who is a professional dancer on the US version of Dancing with the Stars, spoke about being a first-time mum, and said her partner's three sons with Fox were "obsessed" with their new baby brother.

"They are obsessed with him," she said. "They helped choose his outfit for today."

Burgess previously told US Weekly that Fox had also met the new baby.

"She came in and got some Zane snuggle time," she said. "Which was wonderful and really great to see."

It was not always such smooth sailing though, with Burgess previously admitting her first encounter with Fox had been awkward. It prompted her to text Fox.

Austin Green is the father of five sons, including three with Fox, Noah, 9, Bodhi, 8, and Journey, 5.

He also has an older son, Kassius, 20, from his relationship with Vanessa Marcil, also of 90210 fame.