This link seems useful. And I might contact Rick at Ascensus for help. -OP
https://iraresourcecenter.ascensus.com/idcpro/groups/public/@resourcecenter/documents/webcontent/t010601.pdf
Quotes are directly from the pdf link, which is dated July 2024.
Changing Trustees
An employer may wish to change the plan sponsor or trustee for investment options or perhaps other reasons. Such a change requires an amendment to the plan documents. The easiest way to accomplish this is with an “amendment and restatement” of the plan. The phrase “amendment and restatement” also is used to describe the amendment process used to incorporate amendments for law changes into the plan document.
An amendment and restatement of a plan refers to the process of adopting new plan documents with the intent of using the new plan documents as a continuation of an existing plan. The plan generally retains its same eligibility criteria, contribution formula, vesting schedule, distribution options, etc. The amendment merely names a new plan sponsor (and trustee, if applicable). The OFB under the new plan must be at least as generous as under the prior plan (IRC Sec. 411(d)(6)).
Because the plan continues, the employer takes no steps to formally terminate the original documents. The steps needed to change sponsors include the following.
The employer completes the appropriate plan documents provided by the new plan sponsor. The new documents should reflect that the plan is an amendment and restatement or a continuation of an existing plan.
The employer requests, in writing, that the original sponsor issue a check to the new sponsor for the total plan balance, with any necessary adjustments for early withdrawal penalties, etc.
The original sponsor indicates in its files that the plan assets were transferred to another plan sponsor (trustee or custodian). Because the transaction is handled as a transfer, no distribution reporting or withholding is necessary. The employer should provide participants with a summary of material modifications (SMM).
NOTE: Transfers that arise as the result of a change in plan trustee/custodian often are confused with direct rollovers (which are discussed in detail in Chapter 10, Portability). Transfers (which are nonreportable transactions) generally are initiated by the employer maintaining the plan and entail the movement of an entire plan, intact, to a new trustee or custodian. Direct rollovers (which are reportable transactions) are initiated by an employee or beneficiary and represent the movement of such participant’s balance to a completely different plan (either a different QRP or an IRA).