Hello Kevin;

If I understood what you are trying to do, I think the solution is to ue the "Rewire" function in Step 7.

Here is a document showing how to do so with Step 7 v5.x:

https://support.industry.siemens.com/cs/ww/en/view/11791432

I have not used Step 7 Professional v1x to rewire addresses in a S7-300,  the Step 7 Profssional system manual describes the operation this way:

https://support.industry.siemens.com/cs/ww/en/view/109773506/24903260683

Hope this helps,

Daniel Chartier