Yes, but let Miss Manners know when she has your attention. It appears that you were the initiator at every stage, so there were plenty of options. You could, as you said, have continued the first conversation. You could have limited the second conversation, as initially intended. When the second conversation ran long, you could have apologized and ended it. You could have ended both conversations and started a third. Or, now, here's a thought: You could have apologized to everyone and gone back to work.
The rule has not changed, but Miss Manners trusts that you will teach this to your daughter-in-law with your behavior, not by rudely correcting her manners.
[
add
]
[
|
|
...
]