Suggest a way how, with the help of one electrified ebony stick, to inform two identical metal balls of equal modulus

Suggest a way how, with the help of one electrified ebony stick, to inform two identical metal balls of equal modulus, but opposite in sign, so that the charge of the stick itself does not change.

You can connect the balls to each other and bring a stick from the side of one ball. An electric charge is formed on the ball closest to the stick, the sign of which will be opposite to the sign of the charge of the stick (electrostatic induction). And on the second ball the same charge is formed. like the wand. Now you need to spread the balls. Each ball will have a charge of the same magnitude, but opposite in sign, and no changes will occur to the rod.