Blackshirt
Have just passed both in the last three weeks.
As far as I know you can take the GFT in the multi, but dont think you can combine the Multi test with the GFT.
My advice would be to take the commercial in the single, its hard enough without the extra engine to worry about.Also the extra 20-25 Kts is going to give alot less thinking time on the VFR and IFR nav legs. Also an asymetric section In GFT if done combined.
All in all I'd glad I did them separatly !!
All the best
Flying F