Greg, I did find a little information in old newspapers that might be helpful.
Like you I didn't find any Robertson Candy Co. in Canada from the correct timeframe but there were a few ads for a Robertson
's candy in Canadian newspapers in 1909.
Robertson's CandyThe_Victoria_Daily_Times_Wed__Dec_22__1909_.jpg
Robertson's The_Ottawa_Citizen_Thu__Dec_23__1909_.jpg
I found several ads/clippings for Robertson Candy Co. in New York papers here's one from 1909 and one from 1918
Robertson Candy New_York_Tribune_Wed__Sep_22__1909_.jpg
Robertson Candy Co.The_Evening_World_Fri__Dec_20__1918_.jpg
I only found one ad for Robertson-Bradshaw it was from 1918 and it was in a New York paper
Robertson-Bradshaw New_York_Tribune_Fri__Oct_4__1918_.jpg
What I found on the Crown Sweets is interesting, I found this in the New York Times from 1908
Crown Sweets The_New_York_Times_Fri__Feb_28__1908_.jpg
and I found this in the New York Times from 1910 where Bradshaw filed a suit against Crown Sweets
Crown Sweets The_New_York_Times_Sun__Aug_21__1910_ (1).jpg
While I was researching I also found where an individual had a case in supreme court against Bradshaw but I didn't save it and I couldn't find it again.
I found it, I'm not sure if it's the same Edward Bradshaw but it's a clipping from the Buffalo Courier December 20 1911.
Buffalo_Courier_Wed__Dec_20__1911_.jpg