I rarely post here anymore, but your inquiry sounds a lot like the kind we enjoy getting on our own website, so -- since no one else has yet -- I thought I'd take a stab at it...
First of all, Consolidated Kentucky Distilleries was a subset of the companies that were part of the old Whiskey Trust, before Prohibition. They acquired it along with other companies already "consolidated" by the American Medicinal Spirits Company. There was a ton of this sort of thing going on at the time, further complicated by the fact that buying and selling of a "brand" doesn't necessarily correspond to buying and selling of the facilities that actually produce the whiskey, nor the buying and selling of the existing stock (which could be thousands of barrels) of whiskey intended for bottling as that brand.
In the case of your two bottles...
You didn't say what brand they "claim" to have been. That would have been helpfull. But from what you have said, let me note that:
"Sippin Whiskey. 15 years Mellow" tells me that the whiskey was bottled sometime after Jack Daniel's became really, really popular. Everybody was bottling "sippin'" whiskey then. "Ezra Brooks" was a brand that used that idea on their labeling. There was no actual "Ezra Brooks" distillery; the owners of the brand used whiskey from several real distilleries. That didn't make it inferior whiskey by any means; it was just the way it was (and still is) often done. Austin Nichols' Wild Turkey was done the same way.
The "15 years Mellow" part makes me think of the period in the early '80s when the Japanese demand for overaged whiskey really began to shape the marketing strategy of the distilleries and international wholesalers. Prior to that, a fifteen-year-old BOURBON (unlike Scotch) was not commonly thought of as being all that desireable. Since my personal preference is toward "old and woody", I think the commonly-held idea was pooh-pooh, but that IS what it was. The fact that it was touted on the label indicates to me that it was bottled (or at least marketed) after the mid-'70s.
Okay, so it was fifteen years old in, say, 1985. That means it (or at least the youngest bourbon in it) was distilled in, say again, 1970. A whole lot of distilleries no longer existed by 1970, so that might limit our search a little bit.
It's not likely we can ever really put our finger on the exact source of that bourbon, but it's pretty safe to say that...
(1) It's not a hundred years old (and yes, I understand that you realize the difference between a whiskey's "age" and how long it's been in the bottle). Score 1 for your side.
(2) Give your long-sufferin' spouse a little bit of credit, though, in that it does seem to be a bourbon that has some history to it. One might not be able to know just which long-deceased distillery produced the whiskey in the bottle, but one can be assured that, even if this was the lowest-class "straight bourbon" marketed at the time, it was still remarkably higher in "quality" (if you define "quality" as meaning "more flavorful", not necessarily "more sophisticated") than more modern expressions.
Of course, I'm assuming that you intend to open and taste this whiskey. It almost certainly has nearly zero value as a collectible. In fact, you might as well drink it, since the empty bottle probably will sell quicker, and for more, than the full one would.
Bottom line... you win the debate. But your hub gets extra credit, too.
BTW... you didn't say what your 96-year-old neighbor had to say about it. I'll bet there's a great story there, too.