track order of selected items in checkboxgroup for variable amount of options in Shiny

I am using checkbox group as a tool for a user to select some parameters. The things displayed in the checkbox group is dynamic based on files some one uploads. I can get the selected checkboxes, but sometimes, the user needs to select them in a specific order, and shiny will only allow one order, the way it currently is. I'm not sure how to go about doing this, or if there is a widget in shiny that can do this for me. Thanks.