Are you still with us? If I go back to your original post it looks to me like you are cutting out a part then wanting to work on the edges of that part - Although this is possible if you take certain steps to retain accuracy - the perceived wisdom is to do all the work on the part and then cut out the part last. This way the accuracy of all the different zero's is taken care of because you know exactly where the part is.
I have created an example below
Assume I have a 'blank' 600x600x12 with 0,0 Z&Y.
I can create my part in this blank (400x400 rectangle with 25 rounded corners)
Now in order to create a rebate (you say lip) around the edge I can offset a vector inwards the width of this rebate.
The next offset (outwards a small amount) is optional but helps to stop the material 'feathering' on the edge of the rebate when the part is cut out. (You may want to try some using this method and some not and see what you prefer)
You can now also place other features you want on the part.
Create a pocket toolpath for your rebate (and other features) - You need to have created the 'offsets' to form a pocket that is greater than the diameter of the cutter you wish to use. (Remember there are many ways to skin a cat - some users will comment here that they would do an outside profile the depth of the rebate)
Now finally create your profile (cut out) toolpath with or without tabs as necessary
Now you are ready to output the toolpaths to a file for cutting. Make sure you have selected [output all visible toolpaths to one file] and also be aware that the order of the toolpaths are listed is the order they will run in this part file.
shows the toolpaths listed ‘rebate’ before ‘cutout’
Similar techniques are illustrated in the Vectric - Avalon Getting Started Video - https://support.vectric.com/tutorials/V ... video_id=2
Anyway I hope you are still with us
Sincerely and in good faith