So I've been asking around the server if this was a feature, even used the /help command a few times but as far as I saw, no one answered. Essentially I was wondering if there was a way to allow someone access to your house and your chests. I looked around and couldn't find such a feature so I guess there's probably no way, but I'm posting this just to make sure. Thanks!
You can only add guests to your house if it is a premium house. (Permit House) If it is a premium house, open the menu to the house and click View guests, then Add Guests. Thnen type thier username. You can't add people to non-premium houses. (In game cash houses)