To create a sibling to another condition (i.e., a condition that resides at the same level), from the Advanced Condition dialog box, click the Add button located below the condition at the same level. The following screen shot illustrates which button you would click to create a sibling statement at a particular level:
An else if statement, or sibling condition, is created. Think of each sibling condition as having the word "or" before it.
For example, a condition has a sibling condition. If the first condition or one of its child conditions is false, the sibling condition is evaluated.
For information on configuring a newly created if or else if statement, see Configuring an If Statement.