pet and henry

I can't give a positive answer to your questions since I am not the screenwriter to the miniseries. The couple was last shown in Italy and when Amy returned back to London, their continued presence in the miniseries no longer mattered. When Pet gave birth to the baby, it would seem to have "crimped the style" of Henry. So they would have to raise the baby overseas. Even though Pet was a friend of Arthur's and of course would have loved to visit her parents and also became friends with Amy, she had a more important obligation to remain with her husband overseas and raise the baby. Her father probably continued to provide money to the couple. I am sure Arthur and Amy would have invited her to their wedding (as for Henry who was a rival to Arthur, I am not so sure) had she been in London at the time. In the novel, Mr. Meagles asked to be excused from attending the wedding because it would bring back memories of his daughter's wedding and upset his wife. The 2008 movie included the couple at the final marriage scene. I think the scene was changed from the novel because the screenwriter did not want to leave the impression that the Meagles would allow the memories of their daughter's wedding to stop them from attending their friend's wedding.

Other viewers also asked similar questions about the ending and how nothing was shown on what happened to other characters at the end. Some of that could be because of time limitations and cost concerns for filming for the final episode. I think the script dropped their characters after Amy left Italy since they were not crucial to the storyline at that point. In the novel, Mr. Meagles goes overseas to try to help out Arthur and to find Dan Doyce. He comes across his daughter and her husband and Henry decided to have as little to do with the Meagles as possible. That is why Mr. Meagles later asked to be excused from Amy and Arthur's wedding.