Md. Code, Family Law § 10–326

(a) Participation by a plaintiff in a proceeding under this subtitle before a responding tribunal, whether in person, by private attorney, or through services provided by the support enforcement agency, does not confer personal jurisdiction over the plaintiff in another proceeding.

(b) A plaintiff is not amenable to service of civil process while physically present in this State to participate in a proceeding under this subtitle.

(c) The immunity granted by this section does not extend to civil litigation based on acts unrelated to a proceeding under this subtitle committed by a party while present in this State to participate in the proceeding.