The sisters' backstory was especially drawn out. Both of them said the bare minimum about their circumstances, so no wonder we were left with them saying the same thing over and over and over again. And in the end the "reveal" was hardly seismic.
I think they were chosen because Letitia spoke Mandarin and that was a foil for Yin not speaking it.
I was going to suggest to a friend that we apply, we've certainly had enough trauma between us to be considered. But this series has completely put me off doing that!