A proven setup is to put a Yongnuo YN-622C on the camera, then mount the Profoto Air Remote TTL-C on the YN-622C’s pass-through hot shoe. Put additional YN-622C units under each Canon 600EX-RT.

This lets the Profoto Air Remote continue to control and trigger the B1, while the Yongnuo system triggers the Canon speedlites at the same time. Based on the community reports, this setup is reliable and can retain useful Canon flash functions such as remote power control, E-TTL II, and HSS on the 600EX-RT side, though not all of Canon’s newer RT-only features.

If you only need manual control of the 600EX-RTs, a Cactus V6-based setup is another option, but it’s less direct. Using Profoto Air Sync receivers on the Canon flashes would also work, but that is generally the most expensive route and gives only manual triggering.

So the most practical answer is: use Yongnuo YN-622C units, with one sandwiched between the camera and the Profoto Air Remote TTL-C, and one receiver per Canon flash.