Here I have a left armor piece, the body, and a right armor piece. The left armor piece and the right armor piece used to be a mirrored object but I have separated them. I'm currently trying to join the left armor piece to the body, however when I join them the right side changes. At first, I used CTRL+J to join, but that created a new armor piece on the right. Then I tried to use the boolean tool, but that results in the right armor piece being moved. How can I join the Left armor piece without adding or moving other objects?