My chapter has had to deal with this ALOT!!
Its hard to have the parents understand the benefits of joing while at the same time having them "trust without knowing" why their daughters are doing certain things.
When I pledged it was a battle with my mother, but when I became a member we had a Public Induction where all the parents were invited along with other orgs and friends. I know it made my parents feel so much better about what I did and the headaches I gave them doing it