I have been looking at the thread and note that Edward is said to be borne around 1845. I note also that the one of the George McCanns in 1911 census has his age as 83 ie born 1828. While not getting too hung up on ages a marriage at 17 years does seem to be quite young.
Where have you found the possible date of birth being 1845? I know Edward dies 1897 and his death is reported by Teresa NcCann who made her mark. His age is given as 52. I am supposing that this is where the date of 1845 comes from.
I have been looking at the census records for George McCann for 1901/1911. In the first he is 70, is a linen weaver, cannot write and his mark is made. He is RC. The second one, in 1911, a George McCann is a widower, farmer and his signature is made and to me it looks quite assured.
Significantly he has inadvertently, and helpfully (for us) completed the section of the census about children born and still living. This was to have been completed by his wife had she been living. In this in 1911 he states he has 5 children born and 5 children living and was married for 54 years. If his age at 83 is correct and he counts himself as still married though widowed this means he was married in 1854 at the age of 29. Also all of his children are still living at 1911 whereas we know that Teresa McCann was the informant at her husband's death in 1897.
Sadly I think we should put aside for the moment the two census records and possibly the age that Teresa has stated her husband was.....she is shown as not not able to write hence the mark.
I think we may be following good leads with the work that Gaffy has done.
Just looking at the death entry the death happened 4/2/1897 at 3 Croziers Row Belfast.
Here is photograph in Croziers Row in 1911
http://omeka.qub.ac.uk/files/original/4b6098f4487f0958fdd77d6668f5a6f8.jpgDo we have a list of the births of the children of Edward and Teresa McCann in chronological order.
This can sometimes be useful if we match to the naming order adopted in Ireland. Just warning that this is not as slavishly followed in Ireland as in Scotland as the Irish were often attracted by and honoured say a local person they highly regarded. It is a start at least. It may give a few clues.
First born son named after his father's father
Second born son named after his mother's father
Third born son named after his father
Fourth born son named after his father's oldest brother
Fifth born son named after his father's 2nd oldest brother
or his mother's oldest brother
First born daughter named after her mother's mother
Second born daughter named after her father's mother
Third born daughter named after her mother
Fourth born daughter named after her mother's oldest sister
Fifth born daughter named after her mother's 2nd oldest sister
or her father's oldest sister