Corel, good
You can do all of your 'margins' and offsets in Corel before exporting to your machine's software.
How I do this:
My machine has a 1300x900 work area. In Corel I have that size saved as one of my work area's. I also have preset guidelines that borders my work area. What I've done is drawn a box around the perimeter of the table so it's exactly 1300x900. I've colored the outline 30% black, and it's 24pt's thick so I can see it.
The reason for the border: If you've chosen the top-left corner as the 'home' position, then the machine's software places whatever you import to it, say a 3" x 3" plate, in the top-left corner. If that's not where you want it, then you have to move it, which is cumbersome at best with Chinese software. I'm thinking this is why you're looking for an offset function...
However, the border encompasses the entire table, so by default it has nowhere else it can go. And therefore, anything within the border that you're working on has no where else to go either! So if you want your 3x3 plate to be 2" from the top and 2" from the left, just put it there in Corel-- and that's exactly where it will be in your machine's software when you export it!
There IS one catch with this, which is you must turn off the 30% gray so it doesn't engrave. But a benefit of this is, you can type yourself notes in Corel, color them 30% gray, and export them with the job. This is handy for 2 reasons; notes are right there handy, and they remind you to turn off the gray! If your software works like mine, set your gray for 0% power the first time, and it should default at 0% every time you send a job, so if you forget (I still do occasionally), nothing will engrave! Probably wont anyway because it will be running right at the extreme edges...
This is screenshot of my table in Corel, note the border around the table, my 'notes' and the test plate's border, all are 30% gray.
The guidelines, and the plate are 2" from the top left corners..
table1.jpg
This is how it imports into my engraving program,
the plate is right where I want it
- the gray is still 'on'...
table2.jpg
-and this is with the gray off- it's now all ignored by the machine- just send the black and engrave away--
table3.jpg
I use 30% gray, ANY color will work. Also, the 2" margins are just what I use since I have a bunch of 2" wide aluminum bars I use as shims and spacers.
Any zero point you find that works for you on the actual table, make that your zero in Corel with guidelines, from there it's easy peasy...
Hope this helps!