You can link the zoom behavior of multiple dygraphs by specifying a
group when creating the graph. For example, the following code links the three graphs below. Try zooming one chart (done by mouse-selection) and note that the zoom range of the other graphs is also updated.
dygraph(ldeaths, main = "All", group = "lung-deaths") dygraph(mdeaths, main = "Male", group = "lung-deaths") dygraph(fdeaths, main = "Female", group = "lung-deaths")