From the limited information given, it seems there are two choices:
1. Qualify a new weld procedure with destructive testing and test welders to the new procedure.
2. Create a new weld precedure (paperwork) using two existing qualified (either prequalified or by destructive testing) weld procedures and select a welder from your company who is qualified to both of those procedures in the necessary positions.
You must also comply with the requirements of the applicable construction code (B31.1, B31.3, Section I, Section VIII, etc.)and you must have a WPS that covers the work being performed. If the F number is affected, you may not be covered, i.e., a change from F4 to F5 for instance or vice versa.
If a change in employers is involved, all bets are off.
I agree with GTAW, Section IX is not a stand alone code. You must also comply with the requirements of the code of construction like B31.1 or ASME Section VIII Division 1. You can qualify to section IX both processes in a single coupon as long as you list both essential, non-essential, and when required, the supplementary essential variables for both processes. The GTAW electrode will be an F6 electrode and the FCAW electrode is also an F6.
You can also by Section IX, combine two different PQRs into one WPS as long as the GTAW root process is used, and the FCAW process is used in the other as long as all the essential, non-essential, and supplimentary essential variables are within the scope of combining them per ASME Section IX QW-200.4.
Per ASME Section IX, the PQR will most likely be fine. The WPS must include downhill vertical progression. The welder must be qualified for downhill progression.
Double check the applicable ASME pressure piping code to verify downhill progression is permitted or to verify the WPS does not have to be qualified with the position and progression to be used in production.
Never forget what the letters "ASME" stand for; A - always, S- sometimes, M - maybe, E - except. The specific conditions, limitations, and exceptions are often addressed by the applicable construction code.
