Sorry not to reply earlier Vic (yesterday was one of those days)
I've just checked Christian Settipani's book La Prehistoire des Capetiens, which I think Charles Cawley quotes in FMG, and he states that there are about 3 different theories about the parents of Alpäis but basically no one knows for certain and I agree that her LNAB should be Unknown.
Interestingly Settipani also states that Herstal or Héristal is used as the surname for Pépin only from the 13th century onwards. However I think as most modern authors refer to him this way, it would be better to leave this as his CLN.