Questions Import Scenarios: "Update Else Create" function?

In attempt to create an import scenario to update pricing for items in our "Price List", I have encountered an issue that has stood in my way in more than a couple different situations. I wanted to see if anyone on AUG happens to know a way around this issue, since I have a solid example to provide on hand. I am aware that a source field value of =-1 on a <Line Number> action will create a new line, and I am also aware that unchecking the "active" box on this same type of line will cause the function to lookup/update. My question here is, is there a way to cause an import scenario to do both (an update else create) type of function within the same scenario?   

As it currently stands I have two import scenarios built; One for creating new sales price records and One for updating existing sales price records. While this gets the job done, it does cause for a bit of extra work that I would like to cut out of our current workflow. If I could combine the two of these scenarios into one performing both functions without errors through a single import, it would save us a lot of time in the long run. My attempts to combine these scenarios have resulted in a "duplicate price value" error every time, as acumatica doesn't seem to want to overwrite records without being specifically instructed to do so. Any and all feedback/guidance on this would be greatly appreciated.

Thank you,