RHI situation at “tipping point.” Could the scandal bring down Stormont? Part 2

Warnings that the Renewable Heating Incentive scandal could bring down Stormont. Sinn Fein say the situation is at "tipping point". What will happen next and where exactly do Sinn Fein stand regarding calls for a public inquiry? Mixed statements on whether there should be one, is there a split in the party over it?