Vero 13 kickers or separate veg light.

My primary grow light is (5) Vero 29 BXRC-35E10K0-C-73-SE (68Vf, 3500K), approximately 9.5" OC, being driven by a ZPE PF-P400CC-C105-S-DM (400W, 1050mA) (about 340W of 3500K for a 2x4 tent).

I have at my disposal (10) Vero 13 BXRC-40E2000-C-73-SE (34Vf, 4000K), and an Excelsys LXD150-0450SW (150W, 450mA) to drive them.

Should I add the Vero 13s to my existing fixture, or would these cobs be okay to drive a separate 2 plant veg tent (spread 5 cobs around two separate "dedicated" plant fixtures that I could keep close to the canopy)

Your PPFD is already over 1000. I think they would make a good veg lamp.

How do I calculate PPFD and what should I be aiming for in the different growth phases?

You need to know the LER and QER for the spectrum. Then, LPW / LER = efficiency. Wattage * efficiency * QER = PPF. PPFD = PPF / sq/ft * 10.7

Would this be a good tool to find LER and QER?

https://www.rollitup.org/t/photosynthetic-spectral-quality-calculator-psqc.922782/

You gave me some homework to do, Professor. I have been Googling acronyms all night, I am getting a hell of an education in lighting!