BE CAREFUL!!! If you are using cleaners on antiques or collectibles, you can easily remove the finish and very seriously decrease the value of the item. How seriously? By as much as 75%.
Valuable items require professional advice or work. Removing adhesives can be very, very tricky stuff. The solvents that remove the glue can very quickly damage the finish or the actual object.
Even if these are things she is going to turn around and resell, why lose money?
Contact an antiques dealer in the area and have them recommend someone to talk with. If you can't find anyone, check with one of the bigger libraries in the area and see if they have a conservator or preservation specialist who might be able to recommend information.
I used to work in a research library and my mother collected a wide variety of stuff. Ah, the crap, er.. valuable knowledge you learn and remember over the years...