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.

In that case, the Posts suggest having clear, easily explainable criteria about who gets to invite who—for example, only allowing your single attendants to bring an additional person. Or maybe you let your guests know that you’re only inviting plus-ones that you and your fiancé have met before, or known for a certain number of years. Whatever criteria you choose, it’s important that you try to apply it fairly to everyone.

4. Don’t Worry About Returning Plus-One Favors

Even if you were allowed to bring a date to a friend’s wedding, don’t feel obligated to return the plus-one favor (seriously). “Your wedding is—and can be—different from theirs,” says Hopkins. “They may not be happy with your decision at first, so it may be best to communicate and explain why you made the decision you did.” Most importantly, work extra hard on your seating chart to ensure those attending your wedding stag are seated with someone they know, or at a table filled with personalities who will make them feel comfortable and welcome.

5. Include the Plus-One on the Invitation

How do you notify your guest about whether or not they have to fly solo? It starts on the envelope. Very traditional wedding invitations have an outer and inner envelope. The outer layer addresses the recipient (the guest or couple you know personally) and the inner paper then lists all the names of those who are invited, like children or plus-ones. “That envelope says a lot. If it’s your name alone, they are not offering a plus-one. If it is for you and a guest, it will say so,” Harrison says.

This is not always the case, particularly with more modern invitations. If you’re only including one envelope or sending an online invitation, be sure to address all invitees clearly and up-front. If the couple is in a relationship, list both guests by their full names. If you’re allowing a guest to bring a casual date, write your friend’s name and then “and guest.” Try not to make people play the guessing game as to whether they have a plus-one. For save-the-dates, though, there’s no need to specify about plus-ones.

6. Be Mindful When Seating Couples and Single Guests

Draft a seating plan that fosters a comfortable dynamic for solo guests. For singles, there are fewer things more awkward than being sandwiched between an old married couple or a PDA-heavy pair. But creating a “singles-only” table could give off the impression you’re corralling your single pals. Instead, place them between outgoing and friendly couples who they’ll likely get along with. That’s sure to create a more communal feel to the event, and it’ll help them meet people organically.

7. Be Prepared for People to Ask If They Can Bring a Plus-One

Guests who do not receive a wedding plus one may reach out about bringing a guest. Emily Post’s Wedding Etiquette says to first inquire further about this requested addition: maybe your friend’s relationship has turned more serious in the past few months, for example. “When it’s news to you that guest is now in that relationship, do what you can to include his or her partner,” they write.

However, if you don’t have the room, Harrison says it’s okay to reply with something kind, along the lines of: “We would love for you to bring a guest, but this is a very intimate affair.” Do it over the phone or in person rather than email.

8. If Having a Destination Wedding—Try To Be as Inclusive as Possible

Look: Destination weddings are expensive and require a large time commitment for guests. And while no couple should spend beyond their means, it is a nice gesture to allow their invitees to invite someone to join them on their likely multi-day trip abroad… especially those who may not have many other friends at the wedding. That way, it can feel more like an experience or vacation, which is what the couple hopefully wants in the first place.

9. The More the Merrier—If You Help Everyone Mingle

If you opt to be fairly generous with your plus-one invitations, you’ll create an atmosphere in which people can meet and get to know each other, connecting your vast web of loved ones. It helps to have some kind of activity (besides drinking and dancing the Cha-Cha Slide) to break the ice between guests who don’t know each other. Some couples opt for wedding games or activities, like trivia about your love story or a wedding scavenger hunt.