OK, since we're spitballing here I will add my 2c of speculation. What do we know? On SGX and ASX the announcement accompanying the halt refers to "Existing offtake arrangement" and "offtake arrangements" respectively.
In Australian legal parlance, the word "arrangement" is wider than "agreement". That's why the phrase "agreement, arrangement or understanding" is used in legislation, including for example trade practices and tax legislation.
We have agreements with Burwill and arrangements with both Burwill and Starck.
It is certainly possible that the news relates to Burwill only and that "arrangements" refers to the Burwill agreements. It is tempting to say that if the ann was drafted by a lawyer or company sec (which I assume) it is more likely that "arrangements" indicates a wider meaning. But having held positions as Gen Counsel, Co Sec and CEO of a listed co I see this from a few sides. There is a strong preference among senior management (who despite the Corps Act has the final say on wording) to use vague wording where possible. There is also a preference for indicating what's happening more plainly where the news is good (eg conversion of Starck into an agreement).
Accordingly, my punt is that the ann will relate only to Burwill and will consist of consolidation into one agreement plus a change in commercial terms to make it more flexible.
I hope this is not the most significant thing you have read today.
