I take it you are going to File > Export > Descendants to a new file and then upload that file to ancestry?
Yes, that file will contain spouses of the descendants. It won't have spouses of spouses, however. For example, if the second wife of John Doe had two previous husbands, they will not export. Step-children will not be included unless they were "forced" to be a child of a parent who was a descendant. (At either an "add a child" or "add a parent" or "attach a child" or "attach a parent" screen.) Some folks do force step-kids to show as children as step-parents, a practice that I don't agree with.