Oh man, I'm in a similar boat to you and it's stressful. Long story short on mine is Schwab stopped offering the roth option when they bought TDA so I had to move. My plan got "terminated" rather than migrated (not sure of the correct term) to Etrade. I selected plan number 003 and 004 (now it's set to 003 for both). But the advise I've gotten was to file the 5558 by tomorrow with my original 001 plan and work with an ERISA attorney or TPA in the 75 days of extension. I paid for solo401.com in an anxiety filled rush to get some advice and the goal would be to move my plan to eventually to not deal with this stuff again - including every 6 years needing to update the plan docs which I just learned. To me for 1, it sounds like you would file one 5500 because the plans were connected. 2, given they are under two different companies and I don't think you have an issue with succession. 3, I would stick with 001. Obviously not professional advice but that's what I'm thinking from what I've learned but I could very well be wrong. If you find a good attorney / advisor please let me know though! I'm having issues finding one myself.
