|The only to do that is to give them the master password.|
Rather than have some have to slog through all the entries in my vault looking for the ones they may need access to, I exported them to a spreadsheet and then edited the spreadsheet so that it only contained the entries for the important ones. I save that to a USB drive, put the drive in locked fireproof strongbox along with a copy of my will and other important papers, and gave them a copy of the key. They know where the box is and what's in it. If I have to change a password on one of those sites, I just update the spreadsheet on the USB drive.