After the dissolution of the marriage of the spouses

Solve the problem.
After the dissolution of the marriage of the Grigoryev spouses, their seven-year-old son was left with his mother by a court decision. Parents agreed that the father will meet with the boy twice a month. A year later, Grigoryeva got married and in order to strengthen relations between her new husband and boy, she began to interfere in every way with her father´s son. She did not allow the boy to walk on the street where his father could see him, and then took her to her mother in the village. Finding out where his son was, his father arrived in the village and, contrary to the objections of his grandmother, took him to his home. The mother sued the child in court. Grigoriev filed a counterclaim to determine the son´s place of residence.
Give a legal assessment of the actions of Grigoriev. Which body should be involved by the court in a case? What decision will the court make in the above claims?