Wedding planning—and the important task of putting your guest list together—can raise a slew of conundrums.

Your best friend from college, who is a bit of a serial monogamist, has a new girlfriend. Do you invite her? You want to invite your cousins (and their spouses) to your wedding, but your fiancé wants to keep it small. You just made a new friend at work who you’d like to add to the list. Who gets the invite? For many couples, assembling their wedding guest list can be a daunting challenge.

“To the couples out there experiencing this obstacle in their wedding planning journey, I hope you can take solace in the fact that you’re not alone,” says celebrity wedding planner Matthew David Hopkins. “Millions of couples have gone through—or are going through—this difficult stage in the planning process, and have gotten over this hurdle.”

If you’re uncertain about how to proceed with your guest list, Vogue is here to help. Here, find our etiquette guide for guests and plus-ones to help you on your planning journey.

1. Married, Engaged, and Cohabitating Guests Traditionally Receive a Plus-One

As a general rule of thumb, Emily Post’s Wedding Etiquette says spouses, fiancés, and live-in partners of each guest should receive an invitation. “Even if you’ve never met or they are not your favorite people, your guest is part of a package deal,” authors Anne and Lizzie Post explain.

Some of the other hidden guests you should consider inviting on your wedding day? The spouse or significant other of your ceremony officiant, as well as both parents of ring bearers and flower girls.

2. Everyone in the Bridal Party Should Receive a Plus-One

The rules about cohabitation, dating, and marriage go out the window when it comes to plus-ones for your wedding party. Not only does a happy wedding party make a happy couple, but allowing a bridesmaid to bring her new boyfriend, for example, is a small token of appreciation you can offer in exchange for her efforts and support, suggests Amber Harrison, a wedding expert at Shutterfly. Think of it as a “thank you” for every occasion your bridal party has had to organize and participate in over the past year.

3. For Additional Guests, Have Clear Criteria

Hypothetically, if you allow one single guest outside the bridal party to invite a more casual partner or friend, then you should allow all single guests to do so. (“It’s hard to give singles a plus-one and other others,” Anne and Lizzie Post write. “You can risk hurt feelings.”) However, weddings are expensive, and adding so many extra names may not be feasible for a couple and their budget.