Just to make it overly explicit with no room for confusion:
A unicorn in the poly world is defined as a single bisexual woman who is seeking to be in a relationship with a preexisting male-female couple, will be exclusive to that couple (i.e. will not have any relationships on the side), and will be sexually and romantically interested in both the male and female of the couple.
AlmaMay is married, which contradicts the "single" part of the definition. She is not eligible for unicorn status as the couple she would join does not want her husband along for the ride.
Unlike sexual orientation, "unicorn" is not something you can be "at heart" any more than "single" is. In other words, the moment she entered a relationship with her husband, she stopped being single and thus stopped being a unicorn. If she were to divorce her husband and seek out a new couple for a triad, then she would regain her unicorn status.
Unicorn-hunters are defined as a male-female couple seeking to add such a person to their relationship, forming an exclusive MFF triad.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker