Create new instance of movieClip_A to center of movieClip_B

I am creating a farm game and I am trying to drag an object (red spot) over the ground. When the object rolls over a soil square it highlights a different color. I am trying to drop the object onto the colored soil and have it plant some corn. My cornCrop movieClip is supposed to appear in the middle of the highlighted soil. I posted some code and a screenshot. In the code snippet i have some hard-coded x,y coordinates for the corn stalk to appear. How do I get the corn stalk to dynamically appear in the center of the highlighted soil movieClip? Plus, I can see that I should probably use some sort of array for the corn because I don't know how many times a user will want to plant them. I am not sure how to do that either.

Attachment 74453

Code:

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if (bucketCorn.hitTestObject(Grid.Cell_3_1))
                        {
                                var gridID = Grid.Cell_3_1;
                                //addCrop();
                                //myColorTransform.color = 0x00FF33;
                                //Grid.Cell_3_1.transform.colorTransform = myColorTransform;
                                trace("Yogi Bear!");
                                var cropCorn1 = new CropCorn();
                               
                                cropCorn1.x = 50;
                                cropCorn1.y = 400;


                                addChild(cropCorn1);
                        }
                       
                        if (bucketCorn.hitTestObject(Grid.Cell_3_2))
                        {
                                //addCrop();
                                //myColorTransform.color = 0x00FF33;
                                //Grid.Cell_3_2.transform.colorTransform = myColorTransform;
                                var cropCorn3 = new CropCorn();
                               
                                Grid.Cell_3_2.addChild(cropCorn3);
                               
                        }

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Thanks,
Alex