I was searching the net earlier today and discovered this article, which states that R' Wosner's son, R' Meir, learned of his father's death after davening Maariv on the first night of Pesach. He continued the evening and conducted his seder in his traditional fashion, only omitting a dance during nirtzah. He said Kaddish the next day, despite the fact that his father was at that point unburied.
I know, from my grandfather's passing, that directly after one learns of a close relative's death, one becomes exempt from all positive timebound mitsvot,until arrangements for the burial have been completed. However, what is the status of aninut when a close relative dies on Shabbat and one learns of the death on the same Shabbat?
PS. I hope no-one needs ever learn of this in practical terms.