Peter, John, and Mary Ann Hyland are the only siblings I have children for, other than Robert, who also married a Keeley (probably a relative of John's wife Margaret). So I wouldn't expect a lot of duplicates for Catherine, first James, Robert, or second James (I presume the first one died). But you never know. So let's go through them and see.
A few oddities popped up as I added James and Robert. Apparently these same individuals were attached to a different James Hyland as father with a mother named Orney (no first name given), as were all the other siblings. I suspected that these were duplicates so I pursued the records.
One of the problems I was starting to see was that the records for my Mary Ann Hyland's siblings, especially census records, were being attached to the wrong people. For instance, Peter Hyland (Mary Ann's brother who married Mary Ann's sister-in-law, Elizabeth Bannon) appeared in the 1851 and 1861 England censuses, but someone had attached those records to a completely different Peter Hyland. So I had to detach the inappropriate sources.
Fortunately, the source linker provides a warning when the same record is attached to another person. So I was able to start this clean-up process.
I then attached Peter's wife, Elizabeth Bannon, who was already in the Family Tree, and this added all of Peter Hyland and Elizabeth Bannon's children after I merged everyone together. At this point, I had a lot of sources for Peter, including him in the 1851, 1871, 1881, and 1901 censuses. What about 1861 or 1891? A search in FamilySearch turned up widower Peter in 1911 in the home of his daughter Mary, who had apparently married Thomas Kelly. No sign yet of him or Elizabeth in 1861 or 1891.
I also went back and added children (a lot of them) to John Hyland and Margaret Kealy.