Recover Lost Stocks

My siblings and I need help to locate lost stocks, inherited from our great-grandfather, from a privately-held company whose 2021 sale resulted in a large payout for our brother (who had proof of his ownership; we are hoping his experience may have left a trail of crumbs). We have already done a significant amount of research. We have letters and some information but need an expert to navigate the recovery process.

Ideal Skills and Experience:
- Experience with stock recovery
- Familiarity with stock issuers and transfer agents
- Strong research skills
- Financial background is a plus

We are offering an initial fee, plus a percentage of any funds recovered.Please provide a detailed plan and timeframe.