In the end, while I was not able to create a new service definintion (SD) file from a pre-existing service, I was pointed in the correct direction on GIS Stack Exchange. Here is a link to the question I posted over there and the reply.I was able to use a combination of the following solutions to resolve my issues using the ArcGIS REST Administrator API and arcpy.[INDENT]You have several options:Use Python or any scripting language of your choice to modify properties of an existing service. This is done by using ArcGIS REST Administrator API. Here is the sample for modifying properties of an existing service. I use it almost daily and it is very easy to write a script altering properties as needed. This is much more efficient imo than creating a service again from .sd.Publish a service with the required properties directly set by using ArcGIS REST Administrator API and ArcPy. In this case, you will be able to specify the advanced settings in advance. Again, refer to the samples from 2. above to get started.[/INDENT]