I read your charts and admired them, Bill, so I've no excuse for the oversight on John. Too many blinkers, perhaps. Will review them and pay closer attention. The issue of exact relationships, if any, will go on being a contentious one until we have more information. For the time being, it's all just supposition and conjecture. So long as we remember that, we needn't get too hung up on precision just yet. The best thing I can do is focus on finishing what I'm working on at the moment, which should take about another week. After that I'll try to get the tonnes of material I have scattered all over the place up onto the board - that way everyone can sing from the same hymn sheet, or at the very least argue their points of agreement and difference from a solid base of reliable - and referenceable - material. It will help with the speculation, which can't always be avoided.
As for John Halpin, tide surveyor, my feeling was that he had already retired by 1800, which is why I was guessing he was Old Nic's brother. But I'll have to double check things before I can be sure. On William it may well be as you say. But apart from the basic handwritten entry in the Burke's peerage draft, there's not much to go on just yet. I have another candidate to add - James Halpin. Now I know you are aware of him because you've mentioned him to me before. I kept him out of the picture because frankly I didn't have much on him. That's changed recently.
Loosely, I think there may have been three or four brothers, or two sets of brothers - the sets being first cousins. Nicholas, John, James (a wealthy Dublin merchant who had a few burglars hung around the time of the 1798 rebellion), and possibly William. I believe James had at least three sons - Richard, William, and James - and all three sons dabbled in distilling, along with many others in Dublin at the time, including three Greham brothers. There was a fortune to be made overnight in distilling, so that must account for its prevalence at that time. It was a tumultuous period in Ireland's history, and in the pubs, inns and illegal premises set up in Dublin there was a great deal of frank talk for and against reform. Central to the talk of some were the ideals of the Society of United Irishmen, which believed in a political order that recognised Protestant, Catholic and Dissenter as equals, as united Irish men. Other groups were less radical, calling for something like the status quo to be maintained, but for trade to be liberalised (for the guilds, or monopolies, to be broken up). Others still were ultra Protestants and they wanted tough action to be taken against the liberalisers - many ultras came from or lived in Portarlington, which was probably one of the most loyal towns in Ireland at the time (I'll have more to say about the politics of Portarlington another time). So you had a situation in which many forces were pulling in many different ways - hence the instability. Spies were prolific, and one reported to the Castle (this is soon after 1798) that William and James Halpin were about as opposed to the crown as it was possible to be. To make a long story short - years after the trouble had subsided there was an easing of restrictions on known participants in the rebellion, and attempts were made to make more positions available for accomplished Catholics, which would reduce the likelihood of further rebellions. My guess is that many remained fiercely sympathetic to the ideals of a united Ireland, but were less inclined to try to realise them through violent means. Some time during this period, James jnr resumed his connection to the production and sale of alcohol by opening an inn in Wicklow town, where I think Halpins with links to the Halpins of Portarlington were already living and possibly working the land.
I want to stress here the very poor historical overview you've just received, and the very fragile nature of the connections between Nicholas, John, William, James and sons...it's a working model that may well be tossed aside quite quickly. No harm in that. Exclusions are as valuable as discoveries. But at least you get a feel now for the importance I place on the need for an understanding of the context in which the Halpins moved and operated - I don't think we can appreciate their movements, their behaviour, without one. The context is as valuable to me, Bill, as the charts are to you (and everyone else, of course).