Could Sinn Fein swing any Brexit vote in Parliament?

Half-informed American here so I apologize if this seems like a naive question on British politics.

Given the strong preference of many in Ireland to avoid a hard border between the Republic of Ireland and the UK, would the votes of the Sinn Fein make any difference in the outcomes of these very narrow votes in Parliament?

Of course any single vote could swing something; I am asking are the votes close enough on these issues that seven votes would make a difference on a resolution that the Sinn Fein would care about.

(I appreciate that taking a seat in Parliament would involve taking oath. I thought that the stakes might make it worthwhile.)

Edit update: I am not asking if they would vote for or against the current government and I appreciate participation in Parliament would rankle an SF member. However, if that participation could make the difference in a decision that will (1) have consequences for decades to come and (2) have an effect on both NI and the Republic of Ireland - could they and would they make a difference?