将两个或多个Crystal Reports合并为单个PDF

I have a CheckBoxList. If I select two or more values then the CheckBoxList SelectedValues would be passed as a Parameter one by one, and I want to generate the Crystal Report for each SelectedValue in PDF format and I want to merge all the Crystal Report PDF format into a Single PDF format. How to achieve this? So far I have generated only a single Crystal Report in PDF format. In below, I have given the Code about How I had generated the Crystal Report in PDF Format.I have a CheckBoxList. If I select two or more