In the event of united Ireland could DUP attract a significant vote in the Republic / 26 Counties ?

If and when we get a United Ireland the DUP will likely merge with FFG, maybe run under separate banners for a few years etc etc. The 2 parties are very similar in policies of keeping those with money happy and oppose SF in any way they can

Maybe if FG showed an ounce of consistency you'd have a point.
They haven't historically so it can be speculated they won't in the future.

The reason why FG and it's the same for FG predecessors is that FG have stood by what the majority of voters wanted. In 1922 people voted for the treaty. Dev dropped SF when hardliners didn't want to actually listen to people.

Throughout the troubles the SDLP were the biggest nationalist party. Modern SF was a minority. SF only became a big player when they dropped the IRA and the IRA disarmed/surrendered.

The approach FG, SDLP, FF etc have taken is what the majority of nationalists support. Even the modern SF party eventually took the hint and SFs support has risen as a result. It's highly unlikely that SF would be the largest party at Stormont or knocking on the doors of government in the Dail if they had not copied the FG strategy and dropped militant Republicans(now called dissident Republicans).

Your issue isn't with FG it's with voters. FG approach to the border has so successful SF copied it. Aside from the 1918 election militant Republicans have had a horrible time actually getting elected. Those that have stood against militant Republicans have won the majority of nationalist votes since in practically every single election.

Or put it another way FG haven't reached out to militants Republicans because they haven't had to and have been rewarded for doing the opposite.

With regard to the original question - currently they have a seal and their own parliment.

And also currently the rest of the Island has to follow what is essentially 'Dublin Rule' from 'Leinster' House.

At this stage of our so called Democracy we should have better local government with representation in each province and in that way it would be easier for DUP et. al . to exist and indeed be voted for depending on their policies and actions.

We need to look outside the M50 - Yes - I know majority of population etc. but we do not all live in Dublin.

Edit: And by the way the Dublin Government is providing funding for DUP and others on the Unionist side - I've no problem with it because it is indeed a shared Island - but we would need to get the unionist people on board with at least - at the very minimum - their own representation.

The DUP and other Unionists benefit from funding sent by Dublin for infrastructure projects and even the Orange Order.

Here's what the poster said:

And by the way the Dublin Government is providing funding for DUP and others on the Unionist side - I've no problem with it because it is indeed a shared Island 

The DUP and other Unionists benefit from infrastructure funding and funding to the OO and other organisations from the Dublin government.

Read it again, the poster never said 'funded the DUP'

They said:

'providing funding for the DUP and other Unionists'

Unless the DUP are in some parallel universe that only benefits from British money, they are providing funding for the DUP and other Unionists, SF and other Republicans The TUV, PBP, Alliance , those of no political affiliation, Chinese, Polish, etc etc

Some people will defend any kind of nonsense, that is what you are up against.

Would be a big issue too for Heather Humphrey's here and would have been for her predesscor Seymour Crawford. She'd be in a contest with them for a good share of her vote.

The idea that the DUP would ever contest an election south of the (former) border is beyond ridiculous.

Why would anyone in FG join a party reviled by almost everyone and certain to end their political career? Considering they already had the chance to end their careers with a reviled party by joining Renua, and declined

SF will change too, they have changed significantly in the years since the GFA but they won't attract DUP voters imo.

You will get a very defined political landscape in the years after unification like you did with FF and FG after Independence.

Only took 20 years to have the leader of the DUP feted at a FG congress. The ability of FG to forget is the significant thing in that.

The natural home of those of a Unionist persuasion left behind by partition has always been FG, that is just fact.

SF will hold seats and maybe pick up some in the north and I think FF will pick up seats there too - the SDLP will disappear or have another go at allying with FF imo. FG will struggle in the northern counties as they have ignored it electorally since partition.
If the DUP take the spanner in the works approach in a UI (It will be disastrous for them if they do) then FG will stand off them, but if they accept the political reality then I think they will seek to attract votes here and as previously stated the FG demographic will be the target starting with the former border counties.

It is pure nonsense. Not only is a united Ireland a million miles away, the fantastical idea of the DUP either merging with FG or running candidates in the South is a complete nonsense. It is also a sinister attempt to paint those in the South who do not favour a united Ireland as potential DUP voters.

It really is childish stuff to be honest. Best ignored.

still less that FG voters might consider voting for DUP candidates.

This is not a derogatory reflection but I know these people and to state that a current FG voter in Monaghan/Donegal/Cavan/Louth who attends OO marches in the north and who hangs a UJ in their community halls and churches would not be attracted to the DUP if they stand candidates in a UI is a huge stretch tbh.
Not saying that Heather or Neale Richmond would decamp to the DUP but people from their backgrounds in the future could quite conceivably.