I managed to do this, here is the code:
{{tblNews.selectedRows = tblNews.selectedRows.map(({ dateTimePub, image, dateTime, isDuplicate, sentimintIndicator, sim, wgt, authors, ...rest}) => ({
...rest,
added_by: current_user.fullName,
}))}}
@Tess had answered a previous question of mine, which was along a similar path. So I used this, along with ChatGPT - and it works
Finally I've solved a question on the forum..... shame it was my own one