Surely it should be called “The Grand Slam”?!
So there’s no need to think you can’t/don’t include the Community Shield (which you should, Pep does and all clubs around Europe apart from Juventus count their own versions of it in their honours lists), you don’t have to put a number to it.
The Grand Slam sounds better than Quadruple or Quintuple.
Even the “Domestic Grand Slam” sounds good:
Community Shield
EFL Cup
Premier League
FA Cup
Imagine being the first ever Centurions and then the first ever to do a Domestic Grand Slam in consecutive seasons...
Then the season after doing the Premier League and Champions League double...
Anyway, back down to Earth, Fulham away, need to win that first!