Sub Report can't resolve relitave path

I've been having an issue where a sub report has a TTX file as a database with a relative path (".\\Cert_WorksetSpecialText.ttx""). Unfortunately when I open it in the Viewer I receive the Database connection Dialog for that file. If I use hard coded paths for the file it works fine. Also the Main reports TTX has a relative path, and it does not cause any issues.

simplified code is as follows:

     ReportDocument MainReport = new ReportDocument();

     MainReport .Load(ReportFile);

     MainReport.SetDataSource(DataTable);

     MainReport.VerifyDatabase();

     [...]

     ReportDocument SubReportDocument= MainReport.OpenSubreport(SubReportName);

     SubReportDocument.SetDataSource(SubDataTable);

     SubReportDocument.VerifyDatabase();

When displaying in the viewer I receive:

as a work around I trued changing the Database.ConnectionInfo to a static Path by doing the following prior to setting the DataSource:

TableLogOnInfo T = SubReportDocument.Database.Tables[0].LogOnInfo;

T.ConnectionInfo.LogonProperties[0] = new NameValuePair2("Field Definition File", x);

T.ConnectionInfo.ServerName = x;

T.ConnectionInfo.IntegratedSecurity = true;

SubReportDocument.Database.Tables[0].LogOnInfo.ConnectionInfo.Attributes.Collection[4] = new NameValuePair2("QE_ServerDescription", x);

        SubReportDocument.Database.Tables[0].ApplyLogOnInfo(T);

Though on ApplyLogOnInfo it reset the path back to ".\\Cert_WorksetSpecialText.ttx". Not using the ApplyLogOnInfo did not have any noticeable effect either. I had read somewhere that setting the location after ApplyLogOnInfo would do the trick, so I tried:

     SubReportDocument.Database.Tables[0].Location = T.TableName;

This only created an "Connection not possible" error in VS.

I cannot change the RPT files, since our current system required the dynamic pathing in the existing files, and I am only replacing one part of the system which was based on VB 6.0 and a much older version of CR (which stopped working after a server update).

I am currently using the latest update (13.0.16.1954) and tried an earlier v13 as well.

And suggestions or help would be much appreciated.

Thanks in advance.