Query: Ultimate Facebook Plugin & Comments

This is a query at this stage to check my understanding. With Ultimate Facebook plugin installed and working I'm testing the comments features.

1. I post from my site and the post appears correctly on Facebook. Excellent.
2. A comment is added to the post on Facebook and it appears on my site. Excellent.
3. I reply to the comment by entering a comment on my site.

Question: Should that reply appear on FB for the person leaving the comment on FB to see? It doesn't seem to when I try it and I'm not sure if it's intended to or not.

thanks for any help.