Depends on if you mean direct-dependence or some ancestral-dependence. Contingent things can depend on other contingent things in some narrow scope. But a complete answer to "why X?" (e.g., "because Y") should avoid begging the question (e.g., "ok, why Y?").
The Stanford Encyclopedia of Philosophy presents a brief overview that addresses some of the questions you raise:
Furthermore, why does a contingent thing have to depend on a necessary thing?