Problem with cutting open shapes?

OK im work on a part i want to cut out with millmage. A big problem im having is with a tree that is made in 2 parts and one part will slide over the other. I tried to do a profile cut on the outside of the part with a outside offset and it wouldnt let me only cut the outside shape. Then tried to do my slot with a different profile operation and for it to have a inside offset so my dimension doesnt change because i need the slot to be 12.4 mm wide. The only way i could do this is by closing my slot. I feel like there needs to be a way to pick lines that would be cut in the profile operation so you can cut a open shape. I guess i could also try to design my slot to a different size to compensate for this but just seems like a lot of work. Is there a way to make a profile operation on a open shape? Do i need to choose a different operation type? Any help would be great. Thanks

I cut straight lines, which are obviously open shapes. Try looking at your workflow differently, or share your file so we can see what you are trying to accomplish.

This is my file with the straight line cuts…

6m Jpole Spacers.mage (42.9 KB)