@James-Burke-0 ,
In addition to what @PeterJones has explained, the only other thing you could do, is bring up dBASEPlus in the Language->User Defined Language->Define your language...User language drop down box, and then `Save As’ and give it a new name.
At that point, you can play with the settings, keywords, etc… all you want in your own named UDL. Because of the way the entire UDL ecosystem works, however, you’ll lose the ability to use the autoComplete file and the functionList file as well, because of their links to the UDL’s file names that those work with, as well as the overrideMap.xml linkage file, but you’d have JUST the UDL to adjust to your likings and then when you’re satisfied, you could go back to the original dBASEPlus UDL and put the changes that you want into the Dialog boxes for the language and then do as @PeterJones says, and just close and reopen the editor and your changes will be applied to the intalled dBASEPlus UDL definition.
If you don’t need the Function List or Auto Complete capability, you can just use your newly named version of the dBASEPlus UDL to view and edit dBASE specific files.
Just in case this is what you meant you wanted to do, to customize the dBASEPlus UDL without losing the original functionality of the original package. I hope this helps.