Don't put optional plurals in parentheses. Instead, use either plural or singular constructions and keep things consistent throughout your documentation. Choose what is most appropriate for your documentation and your audience. If it's important in a specific context to indicate both, use one or more.
|To find your API key, visit the Credentials page.||To find your API key(s), visit the Credentials page.|
|The value of the parent depends on the values of its children.||The value of the parent depends on the value(s) of its child(ren).|
|You can use a physical linecard, which can contain one or more ports.||You can use a physical linecard, which can contain port(s).|