Thanks Andrew,
I was trying to keep the question as simple as possible (so it made sense to me (gotta be able to laugh at yourself).
In addition to being a residence (of the sister) the applicant also claims the property is “used or occupied for the purpose of religious teaching or training, and actually quotes/refers to s555(1)(e)(iii).
It was the “sister” part I was trying to clarify but I guess if it satisfies one criteria, that’s all they need to do.
Cheers.