Auto enrollment for plans that join a PEP or MEP which was established after 12/29/2022

In a recent webcast on the "IRS grab bag" regarding automatic enrollment,  it was noted that for plans joining a PEP or MEP - "remember - the determination is based on the participating employer and not the MEP/PEP original effective date".  In this case, I believe that if a plan with an original effective date of 1/1/2020 joins a PEP on 1/1/2023, they are "grandfathered" and would not be subject to automatic enrollment.  The webcast did not address when the PEP was established.

However, in a recordkeeper's summary, it is noted  "A pre-enactment single employer plan that merges into a MEP established on or after December 29, 2022 (a post-enactment MEP) will lose its pre-enactment / grandfathered status." 

These seem to be contradictions.  When I look through Notice 2024-2, I do not find any references to PEPs or MEPs.  Is anyone aware of a site that addresses the PEP / MEP establishment date trumps a plan's original effective date?

Cohen & Buckmann, P.C. prepared a summary of the grab bag titled Mandatory Auto-Enrollment is Coming for Some Plans - What to Know

Here is their description on the rules.  I parsed it to make it a little easier to follow

"Mergers, Spinoffs and MEPs. It was unclear how the new requirements apply to plans involved in mergers and
spinoffs. Employers also asked if they could “buy in” to grandfathered status if they became a new adopting
employer in a PEP or other multiple employer plan that was grandfathered.
Notice 2024-02 sets out some basic rules.

• If part of a grandfathered single employer plan is spun off to create a new plan, the transferee plan is treated as grandfathered. This rule does not apply to multiple employer plans.
• If two grandfathered plans merge, the surviving plan will be treated as grandfathered.
• If a new plan and a grandfathered plan are merged, the continuing plan is generally not grandfathered, unless the merger occurs as part of an m&a transaction during the period the m&a transition rule in Code Section 410(b)(6) applies. This provides an option to remain grandfathered if the plan designated as the surviving plan is grandfathered.
• In addition, each employer in a multiple employer plan is evaluated separately. An employer adopting a grandfathered multiple employer plan after December 29, 2022 is treated as adopting a new plan for purposes of the requirements. However, the status of the other adopting employers who joined the plan pre-enactment is not affected.

My take on this in different words is:

• If a grandfathered single employer plan spins of a new plan, the new plan is grandfathered.
• If a grandfathered multiple employer plan spins of a new plan, the new plan is not grandfathered.
• If 2 grandfathered plans merge, the resulting plan is grandfathered.
• If a new plan (not grandfathered) and a grandfathered plan merge during a 410(b)(6) transition period:
  • If the grandfathered plan is the surviving plan, then the surviving plan has the option to remain grandfathered. 
  • If the new plan is the surviving plan, then it is not grandfathered. 
• If the merger occurs after the transition period, then the surviving plan is not grandfathered.
• If any plan (either grandfathered or not grandfathered) adopts a grandfathered MEP, the adopting plan is not grandfathered. 
  • Any plan that adopted the grandfathered MEP on or before December 29, 2022 is grandfathered.