Hi Margaret, just caught up on all the last posts,
Looks like you pretty much have all the information you need with all the documents you have already accumulated with DOB, DOD, marriages, etc. So seems you should be able to add all things together quite well, actually!
I don't have ANY actual certs except my own! But have still managed to ferret out a family secret or two or three....... Much to the dismay of some older cousins whose ears should have been bigger!
Don't think just because everyone liked and cared for Kathleen that it necessarily says anything about the circumstances of her birth. My Ggrandfather was illigitimate -- took his "adopted" father name, his mother lived within the family well respected and loved by her son and grandchildren, and until about a month ago no one knew he was born out of wedlock and his father was not her husband!
Hesitate in making any more suggestions, actually... but one last one and then will leave you to own devices, noticed your post on the Dublin look up for 1901 - "Just in case" they are not at the location you think, might want to fill in with enough details so that they might be located at another location. I'm sure you know from your own look up experience, often hard to determine if it is the right person without at least a birthdate (or guesstimate of it) to compare to....might save some false starts for the looker upper and get you where you want to go faster!
Good luck!
kathy