It is not only possible, but quite common to weld these combinations of materials. If you qualify the WPS by welding a P-No. 1 Group 1 base metal to a P-No. 1 Group 2 base metal and performing the required impact and other tests, you would be qualified to weld any combination of P-No. 1 Groups 1 or 2 to each other or to themselves. This is stated in QW-403.5. The supplementary essential variables must be followed when notch toughness testing (drop-weight or Charpy v-notch) requirements apply in the applicable code section (Section III, VIII, XI, etc.) or design specification.