This routine from Juan Villarreal will combine separate hatch objects into a single object. When you create hatch objects in AutoCAD, there is an option to create multiple hatch objects as one entity or create them separately. If you do the latter, you can use this routine to join them back together. Start by loading the LISP file, then type in the command MH. Choose the initial hatch object, followed by the additional hatch objects. They will be joined into a single hatch object, the properties of which will match the initial selected object. Juan has included some notes in the code as well.