By now, you have most likely created rules for your family, your workplace, or yourself. When you make rules for an open relationship, what you are really doing is making rules for yourself, primarily, the same way that all rules we make are for ourselves. Generally, rules are developed for reactive reasons: we encounter a problem, we create a rule to address it. My cholesterol is too high, I now will only eat animal fat 3-4 times per week instead of 6-7; or, dirt is getting tracked through the house, now everyone who arrives must leave their shoes in the front hallway. There are, of course, times that rules are developed in advance to prevent safety issues, keep order and lifestyle, and maintain schedules.
One of the best ways to make rules when you may end up making several is to begin with questions. How do you define a relationship? What is sex to you? What level of commitment would you prefer, and how does someone show their commitment to you? What do you need your partner(s) to be honest with you about, and to what extent would you like them to be honest? Why do you want to be in an (another) open relationship? What are some of the things that you want to keep from prior relationship experiences, versus some of the things you’d like to change completely or do more or less of?
Draft your rules
Begin to write down your own set of rules based on the answers to the questions.
Go to the bookstore and look at a book on relationships. They often have lists of statements for you to consider as you reflect on what you would like your relationship to be like.
Consider things you rarely do in ordinary relationships, such as rules regarding frequency, duration, geography, logistics. Some of this may be in reference to sex, and some of it may not be. For example, how often do I want to see the other person or people, how long do I want to spend doing particular things with each person, where do I want to see him/her, and who will be responsible for keeping a schedule?
How do you want to deal with things when issues present themselves? How fluid do you want the rules to be?
Since this is a new relationship [with at least one partner], would you like to test it by making more abstract, less-specific guidelines? Or, do you do better with clear, example-based rules?
When something happens that there is no rule for, what are parties expected to do?
What is the best way to communicate, and how quickly should people do so?
Share your rules with your partner(s)
Be open to discussion about what is critical to your partner, but not vital to you. Know in advance that your partner(s) may have a different mental set in his/her approach rule-writing.
Remember that rules are designed to reduce anxiety and increase your presence in the moment. Take your time and allow yourselves to consider what may make you uncomfortable. Decide if there are people who are off-limits, in terms of who you can both involve (neighbors, coworkers, people who have similar tastes to each other). Think about areas; how you will feel if you are in your neighborhood and you see your partner with a different person, do both of you travel frequently, and is there a chance that you might bump into one another with another person in an airport.
Consider writing the final copy of rules that are sensitive in such a way that you are able to tell which addresses an issue that is important to you versus your primary partner. For example, “Because it bothers me when you come in too late at night, but I also hate to sleep without you too frequently, I would like it if you limited your sleepovers with a secondary partner to three times per week.” That way, when discussing issues (even with a tertiary partner) you can identify who had the difficult feelings, to begin with.