Good morning, Doris! Well, in cases like this, it always helps to go back to what you know for sure, and review it and see where it leaves you.
When i look at the info so far, i am convinced that Ronald Edward Gurney, Lorraine Gurney, Effie Belle Gurney and David Gurney are a family group. Except for David, who is younger, they appear together on the 1940 census. This family grouping is totally consistent with family memories at the time of writing Ronald's obituary.
In the 1940 census, this group of siblings are with their parents Thomas and Mary. Thomas is shown there as Thomas F Gurney, and Mary as just Mary. The family member who wrote Ronald's obit thought that Ronald's father was Thomas J Gurney. Census takers were not aware that we would later pore over their handwriting to glean info about our relatives. They just needed to get some names down so they could count them. They were hearing hundreds of names a day. They may have gotten the job because of their connections rather than their qualifications for the work. All of that needs to be considered when reviewing their output. If the informant at Thomas and Mary's household said that Thomas's name was Thomas Joseph Gurney, the census taker may have just caught the 'ph' at the end of Joseph and thus written down F. Maybe the informant was a neighbour and actually thought it was F instead of Joseph.
When considering whether to think the census taker is more credible or the family member who wrote the obit is more credible, in this case i'd go with the family member who wrote the obit. They at least cared about it and probably ran it by another member of the family. The census taker just wrote it down and went away without even showing the page to the informant.
But still there could be some double-checking happening. The birth certificates of Ronald and his siblings should be procured to see what they say. Since their births are less than 100 years old, they are not going to be online. Now we are right back to old-fashioned pre-computer genealogy, when we had to pay money and wait weeks for every tiny crumb of information! But one free bit of research could be happening. Was there a Thomas J Gurney and a Thomas F Gurney both present in that part of Maine at the same time on any of the 1940, 1930, 1920, 1910, and 1900 censuses? Or even another Thomas Gurney or Thomas Gagne of the same age? If so, maybe there are two separate men, and you will have to follow the careers of both in order to sort out who is who. If not, maybe Thomas J and Thomas F are the same person, depending on what his children's birth certificates say.
The children's birth certificates are also the best source of info on Mary's actual last name. Ronald's obit-writer says Brayley and says her family was from Gardiner. (If you are not still living in that area of Maine, you are probably going to have to become familiar with the smaller towns or areas so that you know what was meant by Gardiner and Chelsea. Also, addresses or property ownership could help confirm links between individuals) The marriage index for when Thomas J Gurney married Mary A Brailey in 1927 spelled it Brailey. Here's where you need to research the Brailey/Brayley family of Gardiner. Did they standardize their name as Brayley after 1927? Did the clerk at the registration office in 1927 just take his best stab at it but the family themselves were already standardized as Brayley? Did Ronald's obit writer take his/her best stab at it without checking with the Brailey/Brayley relatives? Ronald's obit was only written 5 years ago. It might be possible to ask the writer where he/she got their info. They might haul out some birth certificates or a family bible....or was the obit writer you as the family genealogist, going with remembered family tradition?
It is unlikely that there were two separate families in the area, one Brailey and one Brayley, and that they were using the spelling to differentiate themselves from each other. But it is still something to consider and rule out. Is there a Mary Brailey and a Mary Brayley both appearing on any single census between 1910 and 1940?
Now Bra*ley versus Bradley/Bradely is another matter. I haven't seen the source for Bradely yet. Can you point me in the right direction to see that? Is there other evidence of such a family in Gardiner at the time?
It is primarily the relatively recent time frame of this research that is slowing you down, because of privacy concerns. Once you get into the next generation, you will probably find smoother sailing until you get into pre-census generations. If this line does go back to French Canada, you will find meticulous record-keeping and even Dictionaries of the families back to the 1600s. So don't give up; just put your work on a solid foundation even if it takes a little bit extra at the beginning of sorting out this part of your family.
Thanks for making profiles for Thomas and Mary and some of the children. Ronald Edward Gurney is well documented at Family Search. Here is a trick i just learned the other day from a video made by Eowyn, one of the core WikiTree team, that maybe you could use to good effect for Ronald. When you are on his profile, look at the top right hand corner where you will see the links to the drop-down menus, Hover over Gurney-909 so you will see that long menu that starts with Compact Tree/Cousin Bait/etc. They are in alphabetical order, so zip down to Research. It is a direct link to FamilySearch, and if you are logged in to FamilySearch already, it will pre-populate the facts about Ronald and run the search before you can even blink. You can even use their clipboard to grab the info to bring it back to paste in your WikiTree profiles.
Cheers
Shirlea