kevlar49-
All three AWS specs are relevant to developing/qualifying your laser weld process. For an aerospace fusion weld AWS D17.1 is the most comprehensive document, while AWS C7.2 and C7.4 are specific to laser welding. I have not read thru AWS C7.4, but I would guess that it provides a guideline for the steps involved in qualifying a laser weld process for an aerospace application. For most aerospace applications, you will be qualifying a weld process that is specific to your particular component and end item/model configuration. And any changes to the component design or weld procedure will likely require you to re-qualify the process. The qualified laser weld process will be controlled by your own internal documentation and CM procedures.
A couple years ago, I went thru this exercise to qualify a friction weld process on a flight critical aircraft drivetrain component. We worked closely with our friction welding source to develop the documentation and qualify the process. We used an ISO specification as a guideline since our welding vendor was already familiar with it. The qualification effort involved writing a detailed manufacturing procedure, producing several representative weld samples based on the written procedure, and then performing metallurgical and mechanical testing on the weld samples to validate the process.
Best of luck to you.
Terry