Defining or non-defining relative clauses?

People ..... move to a big city can find it hard to meet new people.

• who, DC

• who, ND

My sister Jane, ..... lives in NY, has made a lot of friends there.

• who, DC

• who, NDC

The cafe, ..... opened near the university, is a good place to meet people.

• which, NDC

• which, DC

Paul, ..... has just moved in next door to me, has four sisters.

• who, NDC

• who, DC

It's not always easy to meet people ..... like the same things as you do.

• who, NDC

• who, DC

Of all the six flats, the one ..... Sally shares with her four friends is the smallest.

• that, NDC

• that, DC