I think you are misunderstanding the intent of a first article.
The function of a first article is to verify that the process that is intended to be used to produce production pieces has been thoroughly evaluated to be sure that all requirements have been accounted for in the process and that there is confidence that the process is capable of producing product that meets all requirements.
Be careful. That doesn't mean that the process has good capability ratios. It only means that the process has all the requirements in it and it can produce a part or assembly.
If your process is in a state of flux due to changes, improvements, modifications, etc; then a first article is pointless because you haven't settled on an intended process yet.
Now all processes are subject to change and modification, but there comes a point when the producer has settled on a process to be used for production. It is the product of this process (and this process itself) that needs to be thoroughly evaluated as a first article.
All of th parts produced from a process in flux should be 100% inspected to make sure they conform and, if they do, then they are perfectly acceptable product that should be sold as such, unless your contract specifies otherwise.
Good luck.