If you would like to add a In Condition only if the predecessor job exist else ignorecondition, then you have to use May Be Condition.
It is nothing but a Conditional Dependency.
Ex: If JOB-B is depending on JOB-A, but JOB-B have to wait on ONLY when JOB-A isin AJF. In this case we'll give Out Condition of JOB-A as #-JOB-A-OK and inCondition of JOB-B as #-JOB-A-OK 
If you add #- before the condition name that will be taken into account only whenthe job is in AJF.   _{Your Comment}