Can I change the default color for Relationship Lines? Sorry but I didn't found where to change the default color for relationship lines (for constraints and parents) among Theme settings. Since I really really need to do so in the current project. Thanks in advance!
Yes you can, but not on their own, this uses the themes wire color which is also used for many other unselected wire-frame data in the view-port. (See: 3D View -> Wire)