A tribunal of this State issuing a spousal support order consistent with the law of this State has continuing, exclusive jurisdiction to modify the spousal support order throughout the existence of the support obligation. A tribunal of this State may not modify a spousal support order issued by a tribunal of another state or foreign country if the state or foreign country has continuing, exclusive jurisdiction over the spousal support order under the law of that state or foreign country. A tribunal of this State that has continuing, exclusive jurisdiction over a spousal support order may serve as: an initiating tribunal to request a tribunal of another state to enforce the spousal support order issued in this State; or a responding tribunal to enforce or modify its own spousal support order.