Break the following rules into their elements:

a. § 800.

The parties can by mutual agreement elect to terminate their separation agreement.

b. § 52.

A court of this State shall not exercise its jurisdiction under this Act if at the time of filing the petition a proceeding concerning the custody of the child was pending in a court of another state exercising jurisdiction substantially in conformity with this Act, unless the proceeding is stayed by the court of the other state because this State is a more appropriate forum or for other reasons.

c. § 10.2. With respect to a child who has no presumed father under Section 4, an action may be brought by the child, the mother or personal representative of the child, the appropriate state agency, the personal representative or a parent of the mother if the mother has died, a man alleged or alleging himself to be the father, or the personal representative or a parent of the alleged father if the alleged father has died or is a minor.

d. § 107(b). When the mental or physical condition (including the blood group)

of a party, or a person in the custody or under the legal control of a party, is in controversy, the court in which the action is pending may order the party to submit to a physical or mental examination by a physician or to produce for examination the person in his custody or legal control. The order may be made only on motion for good cause shown and upon the notice to the person to be examined and to all parties and shall specify time, place, manner, conditions, and scope of the examination and the person or persons by whom it is to be made.