I don't know other NPC sororities' policy except for my own, and Alpha Gamma Delta allows this.

I had a chapter sister transfer to our Gamma Beta chapter (Florida State) about a year after she was initiated. Her father was re-stationed in SC, and she decided to go to FSU to be closer to her family. I was serving as an advisor on Executive Council at that time, and I remember reading her letter explaining her situation and her desire to transfer and affiliate. We knew she'd make a stellar member of Gamma Beta, and we let them know that!

I know there's an affiliation fee involved as well as a vote taken by the new chapter (their EC had to approve it as well, IIRC). She transferred, affiliated, and within a small amount of time I heard she was their VP-Recruitment!

On the other end of the spectrum, we've had sisters transfer to campuses with Alpha Gam chapters, only to find out that they didn't really 'mesh' well with the girls there, so for reasons only known to them, they decided not to pursue collegiate affiliation and did not participate in any collegian activity. They became active members of their alum groups, though.