How to create a subscription for the main report which contains subreports in it in ssrs

Hi I have an report which contains the reports body having 3 Table data regions.

and I have an Reportdetials table

here " ReportName"  is the report parameter contains these three A,B,C report in the parameter drop down selection

and the Month and Year parameter follows this report

I will create a subscription for 3 reports and repective month and year parameter in the report , I need an single export in excel contains these three subreports 

sheet1 : A report ,Sheet 2 :B report ,and Sheet 3 : C report I need like this my report export in excel

for the respective month and year parameter selection 

how do I create this kind of subscription in ssrs.