Here's the thing.

I develop a COM control using ATL in VS2015, and implement the IPersistStorage and IPersistStreamInit interface(through template in ATL), I register the control and Open a existing excel file ,and Add controls via COM add-ins.

My Question : How to save the control's data to the existing excel file. When I open the file next time , the data saved in control last time can present.

plus: first, my excel file is common file storing data; second, I can not find the container application(namely excel file)'s store interface！ third, excel file as a compound document，Whether the IStorage interface is implemented？if not,any other Interface I can use?