I would ask yourselves one question first. What are you hoping to gain from transitioning from swinging to poly?
I can see where this might scare her off...perhaps she will see it as you want her to stop exploring sexual relationships of any kind with others to create a safe sexual triad. What will you really be able to offer her? What does she want out of life that this dynamic could hold her back from....kids, marriage, freedom to introduce her hubby to her parents and co-workers with the knowledge he has a wife?
Just things to ask yourself.
Playing the Game of Life with Monopoly rules.
Monogamy might just be in my genes
Poly Events All Over