Yes! Grandparents and other relatives can save photos/videos as well as delete their own comments by doing the following:
・App Version: Open the Album tab and tap a photo or video. Tap the menu icon in the top-right corner, then tap "Save."
・Browser Version: Click a photo or video, then click the "Save" button.
*Grandparents and other relatives can only delete their own comments. However, album members not allowed to comment also won't be able to edit or delete their comments. In this case, please contact one of the album's parent members.
・App Version: Tap and hold a comment to edit or delete it.
・Browser Version: Click the X button next to a comment to delete it.