While working with crystal reports you will noticed that when you use sub report with another sub report or if you use a control under sub report it gets overlapped. It is because the Sub report that comes first expands its size and come over other control or subreports.
The solution for handling this i.e. Sub report automatically expands and shifts other control according to its size is through multiple sections in sub reports.
For multiple sections in sub reports
goto section expert
select details section
click on insert section button
Now you can move other sub reports to next section and you may noticed that your problem related to overlapping of control gets resolved automatically