SAS: dataset name Remove the date and replace with the current date

[78282219]

I currently have a macro which moves my dataset from one branch to another. In each movement, the date is updated. However, I am having trouble with removing the old date autonomously before inputting the new date, any advice?

The code is:

%Macro Merge_Branch(Branch = , Filename = , Library = );

	%Let Timestamp = %sysfunc(putn(%sysfunc(date()),yymmddn8.));

	%if &Branch. = Latest_Commit %then %do;
		
		Data LC._&Timestamp._&Filename.;
		set &Library..&Filename.;
		run;

	%end;

	%else %if &Branch. = Staging %then %do;

		%Let Filename = _20180909_Financial_Input;
		%Let Filename_temp = %scan(&Filename.,2,'_');
                %Let Date_String = %scan(&Filename.,1,'_');
                /* this is the section where I get stuck the dash is a subtraction i.e. I want to remove the date and just have the string*/
		%Let Filename_Stg = &Filename_temp - &Date_String;

		Data Stg._&Timestamp._&Filename_Stg.;
		set LC.&Filename.;
		run;

	%end;

%mend;

Input data can be made like this

data LC._20180909_Financial_Input;
var var1;
datalines;
1
1
1
1
;
run;

%Macro Merge_Branch(Branch = Staging , Filename = Financial_Input, Library = LC );

/*Note, in this macro the library is not important because it will always move from LC to STG*/

[VDD]

is the - a typo

%Let Filename_Stg = &Filename_temp - &Date_String;

should it be 

%Let Filename_Stg = &Filename_temp_&Date_String;

[78282219]

It's more like a subtraction so i'm trying to make the following happen

_20181009_Financial_Input - _20181009_ = Financial_Input

then in the next step I will create a dataset name where there will be the most recent date (in this case it is the most recent date but in future there will be discrepancies)