I think at core we are asking them to make an offer with...

I think at core we are asking them to make an offer with incomplete geostatistical information (on the resource yrs 11 to 20).*
The offerors are doing their assessments with what they have adjusting geostatistical and variography models to accommodate it to inform their offers (or not).
Nevertheless, frustration is reasonable.

All IMVHO.
* in comparison OZL made Havilah an offer for their project with three different levels (legs) of payoff based on Cu price, total production and most important, base payment or not, based on check drilling and mining studies over 18 months. The BHP took OZl over and payoff became even more questionable. I am/was happy to take on all conditions because of my knowledge of the people who did the initial work for Havialh. This week it has offset the most recent RXM hit (for me).