How to write expression in ssis to move dynamic file from main folder to archive folder on FTP server..any help would be really appreciate. ?

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SQL-Server-2012

I have a package that run's on weekly basis.. I need to move file from main folder to archive folder on FTP server.

so how to create expression for below files name:-
ABC.FSR_Satrtdate20200131_date20200221
ABC.FSR_Satrtdate20200124_date20200214
ABC.FSR_Satrtdate20200117_date20200207
ABC.FSR_Satrtdate20200103_date20200124

What I have tried:

I tried to build the expression like @[User::FileName]+Replace(Substring((DT_WSTR,30)GETDATE() ,1,10)),"-","")+"_date"+Replace(Substring((DT_WSTR,30)GETDATE() -7,1,10),"-","")+".txt"

but getting error. Any help would be really Helpful.