Add all of these assemblies:
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;
using CrystalDecisions.ReportAppServer;
using CrystalDecisions.ReportAppServer.ClientDoc;
using CrystalDecisions.ReportAppServer.Controllers;
using CrystalDecisions.ReportAppServer.ReportDefModel;
using CrystalDecisions.ReportAppServer.CommonControls;
using CrystalDecisions.ReportAppServer.CommLayer;
using CrystalDecisions.ReportAppServer.CommonObjectModel;
using CrystalDecisions.ReportAppServer.ObjectFactory;
using CrystalDecisions.ReportAppServer.Prompting;
using CrystalDecisions.ReportAppServer.DataSetConversion;
using CrystalDecisions.ReportAppServer.DataDefModel;
using CrystalDecisions.ReportSource;
Download the attached app that I wrote to get/set parameters, on the right side there is a dropdown function to get subreport.
How To: Parameters in Crystal Reports for Visual Studio .NET
No there is nothing built into BOE products.
CR Designer does by clicking on the subreport options:
Don