For what you are describing you would want to use a trigger on the table where you want the soft delete to cascade from.
Here are a few references on triggers:
Triggers have their place but they can quickly get out of hand when triggers fire other triggers or when the trigger execution takes a significant amount of time to complete.
Additionally performance degradation can be a factor with triggers as they happen synchronous when an insert/update/delete statement is made on the table which can extend the execution time of the statement.
Info from Paul White on triggersInfo from Paul White on triggers