YM, agree. Fair value based on NPV is one part of it. I think it's also important to understand the possible stream of cash flow going in and out of the project and for each party involved.
If Teck ends up with 70% of the cash flow because they need to sell 30% to a partner, it's not the same as if they can keep 100% of the cash flow. In all situations, the total NPV of the project should remain relatively the same, but the NAV for each party is completely different.
Per example, if Teck has an option to stream gold that would allow them to keep an addtional (e.g 300M) net cash flow per year (mine life), that could immediately increase their NAV (8%) by about 1.6B vs. transferring that NAV to the partner.
Therefore, I could easily see Copper Fox asking for an additional 400M over 25% of the NPV (8%), just because Schaft Creek offers this possibility.
MoneyK