The article reports that an individual named Mary Grace Piattos has been included on the list of witnesses for the impeachment case against Vice President Sara Duterte. This information comes from a headline within a collection of news items, but the article content does not provide any further details about the witness, their role, or the nature of their testimony. The impeachment process against Vice President Duterte has been a subject of ongoing political attention, and the inclusion of witnesses is a key step in building the case. However, the specific circumstances surrounding Mary Grace Piattos's involvement remain unclear from the given text. Without additional information from the article body, it is not possible to elaborate on the witness's background, the evidence they may provide, or the official body handling the impeachment. The headline stands as a notable development, but the lack of substantive content limits a full analysis of its implications.