D-Day brought forward? Inquiry or Investigation? Will it matter?

After the First Minister gave an initial curt ‘No’ to Sinn Féin’s draft paper for an Independent investigation she has now given a more detailed and lukewarm response to the proposals:
“However, with the exception of the issue of stepping aside, we believe that the proposals provided to us by Sinn Fein on Thursday and published by them today provide a basis for taking an investigation forward.

“Officials have raised a number of technical issues in relation to the proposals, however there do not appear to us to be any insuperable obstacles to agreement being reached.”
However, the robust words of the Finance Minister Máirtín Ó Muilleoir yesterday sum up the proposal that DUP cannot and will not address:
“We’ve served notice. The only way we can clear the impasse is for Arlene Foster to step aside.”
Sinn Féin are meeting in Belfast today (Saturday). Their motion is due to be debated in the Assembly on 16th January.
However with their Executive partners steadfastly against the stepping aside of the First Minister and the opposition parties attacking Sinn Féin’s proposal for an independent investigation rather than a public inquiry is there any point in putting it forward?
The parties know what the issue is and there is clearly no compromise that can be reached. D-Day may not be 16th January. It might come a lot sooner than we expected.