Without seeing the original contracts I cannot provide a definitive answer, but it would be my expectation that the advertising content belongs to the company placing the ad. The magazine publisher would normally own the editorial content only. Advertising copy is usually provided in a fully completed form, and the publisher just has to drop it on the page.
Things quickly get complicated with freelance (vs. staff) writers, photographs provided by third parties, etc. Given the passage of time, the presumed loss of original contracts, and the fading memories of the people involved, there will always be some ambiguity.
As with most copyright disputes, the stakes are so very low that nobody is ever going to litigate the matter because the costs far exceed any possible recovery. Breen was a rare exception, and he was apparently financed by third-parties with an ideological basis.