A policy of health insurance may contain the following provision: “Insurance with other insurers: If there be other valid coverage, not with this insurer, providing benefits for the same loss on other than an expense incurred basis and of which this insurer has not been given written notice prior to the occurrence or commencement of loss, the only liability for such benefits under this policy shall be for such proportion of the indemnities otherwise provided hereunder for such loss as the like indemnities of which the insurer had notice (including the indemnities under this policy) bear to the total amount of all like indemnities for such loss, and for the return of such portion of the premium paid as shall exceed the pro rata portion for the indemnities thus determined.” The phrase “-- Other benefits” shall be added to the caption of the provision set forth in subsection (a) of this section if the provision is included in a policy that contains the policy provision set out in § 15-222 of this subtitle. A benefit provided for the insured under a compulsory benefit statute, including a workers’ compensation or employer’s liability statute, whether provided by a governmental unit or otherwise, shall be considered “other valid coverage” of which the insurer has had notice. The insurer may include in the provision set forth in subsection (a) of this section a definition of “other valid coverage” if the definition: is approved as to form by the Commissioner; and is limited to: coverage provided by organizations subject to regulation by insurance law or insurance authorities of this State, another state, or a province of Canada; and any other coverage the Commissioner may approve for inclusion. Unless defined otherwise, “other valid coverage” does not include: group insurance; or coverage provided by union welfare plans or by employer or employee benefit organizations. “Other valid coverage” may not include third party liability coverage.