I make it that Tamaya have to get hold of about 5 million shares...

I make it that Tamaya have to get hold of about 5 million shares in order to get the 90% holding.

That's 5 million dollars - would the co. buy on the open market I wonder? Probably not, as the offer is scrip and not cash.

The key here is control. As Tamaya now have control of the project. They would be able to create a structure where Tamaya get all the proceeds and IBR is just an operating company. I have seen similar situations in the past, where majority stakeholders arrange things to their own advantage and to the disadvantage of the minority. Moreover I think the management would be justified in doing so in this case.