Finalizing H&W 5500's & can you file a final < eoy

[TPApril]

generally when we create a wraparound plan doc merging H&W benefits that filed their 5500's separately, we file the original plans for the full year as a Final with zero participants in the same year the new plan starts.

example:

501, 502, 503 - 12/31/16 filed with count of 150 each

510 - new plan effective 1/1/17.

501, 502, 503 - 12/31/17 filed as final with zero count

510 - 12/31/17 includes all Sched A's

is this generally what's done?

corollary question: one of the plans being merged is a 6/30 plan. It is now March and we know the next filing will be a final with zero count. Can we file that 5500 (6/30/16) prior to the period actually ending?