Sinn Fein and how do they form a government dilemma

They took action as soon as an investigation into McMonagle began. They tool action against those involved in the references. The police don't need SF's assistance there if a crime was committed.
They reported O'Donghaile to the PSNI and the Social Services in the jurisdiction were it occurred.
They handed the file and the file on Stanley's case to the gardai.
Was there an obligation to report O'Dongaile to the Gardai when they had no evidence he had done it here? I don't know.

And they need to again recognise the failing and review and fix protocols if they had a legal obligation to do that as they have done in the McMonagle case.
I'll probably get slammed for saying this, but as it is rolled out ad nauseum and to the point of parody elsewhere, I think that ''lessons needed to be learned' from Adams etc and they have demonstrated that they are 'learning from the lessons' and look like they will continue.

Good: any seat gains at all; retaining all the ones where the TD elected for them in 2020 is retiring or is now running against them would both be seen as good wins at this stage

Bad: under 25, which is looking very likely now.

There aren't any lessons to be learnt, they know exactly what they're doing and it's done purposely. Ie keep everything away from the authorities until they have no other option.

Take BS, an uncriminal allegation is made against him, he makes a counter possibly criminal one, they ignore it and find him guilty of gross misconduct. He has enough, resigns and goes public breaking the omerta. Hey presto straight to the guards so no one in SF can possibly comment on the matter.

If BS had kept quiet, accepted his fate which was probably being replaced on the ticket all along, this possibly criminal matter would never have seen the light of day. That's how it's worked all along but the good ship SF is starting to creak.

In the two other cases, they acted on what the authorities did in one and informed the authorities in the other.

Your theory may very well be correct on the Stanley issue but raises questions too.

How do you know the finding against him?
Why didn't Stanley go to the Gardai himself and how should they have handled an internal complaint?

She also said they don't know if it was criminal or not and it's with the Gardai to decide. She takes responsibility for the decision when she was made aware of it. Presumably because there was a 'hint' of criminality.

Not days, years!

In O'Donghaile's case SF could have awaited the PSNI decision not to prosecute and never said anything, and nobody would ever have been the wiser.

Instead, they removed him from the senate and the party.

I have already said the tribute was OTT, but I can see why she was in an impossible position, say nothing and raise a controversy when someone is in a bad place mentally or issue a statement and move on.

And I have said if it emerges that his mental health situation was a concoction between him and SF then that is indeed a resigning matter.