A question:
Does the tag read Phrag. ( Grande 'Vista' 4n x Waukanee) or Phrag. Grande 'Vista' 4n x Grande 'Waukanee' or Phrag. Grande (Vista 4n x Waukanee)? The placement of the parenthesis here makes a difference. If the tag reads exactly as you have written it above, then I would conclude that you do indeed have a Phrag. Grande.
Just my additional cent,
Adam