There is clearly some major misunderstanding of synthetics and...

There is clearly some major misunderstanding of synthetics and the mechanics of shorting.
1) There is no way to cover a short without the broker or prime broker actually buying the shares or buying a synthetic(option or swap/cfd) that achieves the same economic outcome as buying the shares. If the exposure is covered by buying a synthetic, whoever sells the synthetic would normally need to hedge their exposure which means they would ultimately need to buy the shares. At some stage 16 million shares will need to be purchased.
2)If you are short 16 million shares at an average price of 2.5, you would need to lodge collateral of say 110% or 44 million. Assuming you have sold the shares for 2.5 or 40 million you would require additional margin of 4 million. Each day a mark to market occurs depending on the value of short position (BRU share price)and the collateral to maintain the collateral at 110%.
Should the shorter not be able to post 110% collateral, the broker will buy back sufficient shares to ensure the value of collateral equals 110% of the short.
At current levels of 1.85 on a 16 million share short position, collateral of 32,56 million is required. If the share price jumps to 1.90, 3.344 million collateral is required or an additional 880,000. If the shorter is unable to top up the collateral, then the broker will need to cover there exposure by buying back +/- 4,800,000 share at 1.9. The lender then will have a short position of 11.2 million shares against collateral of 23.44 million. (32.56 million he has lodged less the cost of buying back the 4.8 million shares at 1.9 or 9.12 million). The collateral is now back at +/- 110%.
I am sure you can see some of the glaring problems:
The broker will not be able to purchase 4.5 million shares at 1.9.
The broker will not do this for nothing so factor in brokerage.
Therefore you can assume that this short position is held by a large hedge fund that has no problem lodging the additional collateral. The average short level was a lot higher then the current share price so we have some way to go before we see a short squeeze.
Also often these hedge funds are a lot clever then all of us, with very deep pockets. Lets hope that in the long run they gett this one wrong and we do see a short squeeze.