I believe my question was not clear enough ... so I'm going to try again.
Lets say that you are an accredited lab ... and you are being audited to maintain your accreditation. You seek to add a couple of methods to your scope which are developed by the lab based on a published method. You reference this published method in the references section of the method ... would you need to be accredited for the published method aswell as the lab method ... or do you only seek accreditation for the lab method because the published method is considered to be scientifically sound by industry and regulating bodies ?
Thank you.
Given this scenario, the scope of accreditation will likely reference the published method, not the distilled method.....
Incidentially, taking the published method (e.g., ASTM), referencing that method and only distilling it in order to add specific detail like "Use this fixture" or "Turn this switch" is usually not considered "lab developed" and usually does not require separate validation, except for the specific detail added for your specific lab and equipment.
Of course, double-check with your AB, as they may have specific rules for such distilled procedures.
Hope this helps.