I'd probably set the "Primary" Behringer as the Wordclock Master. Set the RayDat to sync to ADAT #1 Input. Then, set the second Behringer to sync to its ADAT Input. Behringer #1 then specifies the frequency for the entire system.
You can also have the RayDat act as the Wordclock Master, and set both Behringers to sync to ADAT Input. If you do it this way, your Audio Software will be able to change the RayDat's sample rate and the Behringer converters should follow along (limited to 44.1k or 48k, no 88/96k on those ADA8000's that I recall).
Beware that there are reports of flakey ADAT Clocking on some ADA8000's (seems like I read about one once every week from somewhere!). Trying different master/slave setups until you find which one is the most solid in your setup is probably the best action when dealing with gear of unknown stability IMO...
As far as how you should configure the 16 Channels of analog I/O in your setup - that's totally up to you and what you need to accomplish with the system.
MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8