usa a função IncDay do próprio Delphi; Returns a date shifted by a specified number of days.
Unit DateUtils Category datetime routines Delphi syntax: function IncDay(const AValue: TDateTime; const ANumberOfDays: Integer = 1): TDateTime; C++ syntax: extern PACKAGE System::TDateTime __fastcall IncDay(const System::TDateTime AValue, const int ANumberOfDays = 0x1); Description IncDay returns the value of the AValue parameter, incremented by ANumberOfDays days. ANumberOfDays can be negative, to return a date N days previous. The time of day specified by the AValue parameter is copied to the result. [As partes desta mensagem que não continham texto foram removidas]
