Bypass pay?
Well, most CoS 99 Second Officers are completely unsuitable since they haven't been assessed. And with no more upgrades needed, no more assessments. Hence no more suitability, and no more bypass pay. Year 4 pay scale indefinitely.
As for the CoS 08 Second Officers, bypass pay is automatically triggered when a DEFO or DEC bypasses you after you've done 3 years making bunks. Any bypassing before that doesn't count. But you could well see CoS08 SOs collecting bypass pay before Cos99s.
Truly beautiful system, isn't it? Creating a winning team for the future.