Brother reads forged letter at our father's wake to cut me out of the will and family wedding

I'm in New South Wales and I need some advice about what my options are after my brother Marcus pulled a stunt at our dad's funeral wake that has blown up our entire family.

At the wake, Marcus stood up in front of everyone—about forty people including extended family and my sister's fiancé—and read out a handwritten letter he claimed our late father had written just before he died. The letter said Dad wanted Jade excluded from the will, banned from helping plan my sister's wedding, and not involved in the funeral arrangements. Everyone just sat there stunned. I confronted him, told him he was lying, and walked out.

I was shaking when I got home. The handwriting looked familiar but something about the date caught my eye—it was dated three weeks before Dad's death, but Dad had been in hospital for six weeks before that with no visitors except immediate family. The ink also looked too fresh. I called Priya, who's a graphic designer and knows her way around document software.

Priya looked at a photo of the letter I'd taken. Under magnification, she found clear evidence of digital manipulation. The signature was lifted from an old birthday card Dad had sent me in 2020—she could see the pixel boundaries where it had been pasted in. The date had been altered from 2019 to 2024. The whole thing was a fabrication.

When I confronted Marcus with the evidence, he flipped the script. He pulled out a text message he claimed I'd sent him last month threatening to "ruin the wedding" if he didn't give me half the house. Except I never sent that message. He'd manufactured that too, probably using one of those fake text generators. Priya checked the metadata and the message was sent from a number that doesn't match any of my devices.

We took the forensic analysis to the family solicitor—the one who drafted Dad's will. She confirmed the letter was a forgery within five minutes of looking at the original. Marcus is now backed into a corner, but he's still refusing to cooperate with any mediation. The will leaves the family home to both of us equally, but the probate process is stalled because Marcus won't sign the paperwork. My sister's wedding is in six weeks; Marcus has been uninvited from planning but is threatening legal action to force his way in.

What are my rights? Can I apply to NCAT for an order compelling Marcus to cooperate with the probate? Should I file for a family provision claim in the Supreme Court if he keeps blocking the estate? My solicitor has mentioned the option of mediation, but Marcus has already walked out of two sessions.