I'd read about the stacking ability in Lightroom and thought I'd give it a go when processing images from a Trash the Dress shoot, hopefully using the "Auto-stack by Capture time" feature. But I couldn't work out how to do it. My workflow when working from multiple SD cards is this:
I was trying to stack images held within the "Quick Collection", but all of the the stacking menu items were greyed out. So, I went to the "Previous Import" collection, and looked at the menu item, and there were some enabled items and I could select "Auto-select by Capture time". So, I then created a new Collection to hold my photos and that didn't work, neither did using the tags to select the images. So, the only way I seem to be able to do it in a collection is either by auto-selecting "All Photographs" or "Previous Import".

Thanks to this forum I've discovered that stacking within the Folder view works, and fortunately, all my Trash the Dress photos are in the same folder and so this is what I've resigned myself to having to do.