SFD/SB is just the "Phase", you pick a phase and follow those rules, w/e rules they may be. Treat it like on page 176 of the BR, there are 6 phases, SFD says you can use the 1st 5 phases.
When playing it in mind this way, it becomes a lot easier to read the rules. The SFD rules says "as if it was that phase" So treat it like so in the rules.
I think the rules are extremely easy to understand in this mindset.
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AoS: BoC 9k, CoS 3k