Start-up (sort of?) 401(k) Plan

Here is the situation.   The prospect (S corp, just husband and wife) has started 401(k) Plan in 2021 using the free plan doc from Fidelity(?). Year-to-date no contributions/deferrals have been made so the account is sitting pretty with a zero balance.  Obviously, that Plan Doc does not allow for any "fancy" stuff like Voluntary After-Tax ("VAT") contributions.   Now the prospect would like to do the VAT contribution and do In-Plan conversion to Roth (for 2021 - what else is new - why not wait until New Year's Eve?).   So, I am trying to think through viable options (given we are already in December):

1) Take the Plan and restate it on our plan document system, have the additional brokerage account opened (to accept VAT and conversion to Roth in the Plan) and help the prospect to get it done.   I am concerned that Fidelity might not accommodate the existing account without them sponsoring the Plan doc.  And it might take some extra time to sort it through which will diminish the opportunity to meet the objective by December 31

2) Leave the Fidelity Plan alone (and not fund it at all) and start a new 401(K) Plan for 2021 using our platform.  That would leave an "empty" plan for some time and then later on I would terminate it.  The shortcomings are having an extra Plan lingering around, cost of termination, extra 5500, etc.   The whole nonsense but squared....

3) Terminate Fidelity plan and start another one.    Obviously this triggers the "replacement" plan issue.  But the Fidelity Plan is empty and it should have never existed in a first place?

All thoughts with pros and cons are appreciated.  I apologize in advance if this does not make much sense because I am not a "401(k) guy" but unfortunately an actuary.   Thank you.

Wasn’t January 30, 2022 the deadline to contribute the after-tax contribution for a plan year that ended December 31, 2021?

John is correct if you're really talking about 2021. If you're talking about 2022, I would only choose option 1. The other two don't make any sense.

I was talking about 2022.

13 minutes ago, Bill Presson said:

I would only choose option 1. The other two don't make any sense.

I agree with this. And you may already be aware of this, but with Fidelity, the magic words are "non-prototype account" when you are setting up an account with them but not using their document. Otherwise they will try to set up yet another plan...