Happy to hear it!
Any time you are building legitimacy, you are doing so within some kind of hierarchy, even if it is just "you and her." There is some kind of order of people being established.
It's possible for others to respect legitimacy you have in a hierarchy other than their own. For instance, you may acknowledge a certain degree of legitimacy in a religious or political leader from a religion/political ideology you do not subscribe to. However, the legitimacy such a person holds for you pales compared to that of someone in a hierarchy you see yourself as part of.
Offhand, I'd say legitimacy comes down to effectiveness and alignment with the group. If you are either ineffective, or not aligned with the interests of the group, the group will increasingly come to view you as illegitimate. There's a lot that goes into both of those, of course.
I might do a follow-up article and talk about building legitimacy there.