If your client has made that considered choice, you'll want to read carefully (and consider the perspective of a challenger who seeks to invent an ambiguity) to catch everything and negate all the unwelcome interpretations.
I've done documents of the kind you describe. It can work if you sweat the details.
If this is for a participant directed plan, you are going to need to update the 404a-5 notice and distribute that notice 30 days prior to the effective date of the change. You can add a cover letter to the notice that it is being updated for fee changes.
I get the recordkeeper tends to want the TPA to "approve" the payment in the sense you think it is complete and accurate....
I would stay out of the approving business in the sense making the go/no go decision.
As others have said get someone at the plan sponsor to put in writing to pay or not pay these people. If they can't or won't do that maybe they will final solve the issue of no trustee that is an employee.
I am pretty sure my bosses would back me if I told them I am not going on the recordkeeper's website and saying pay these people without written direction from the plan sponsor.
You can use Reliance Trust Company to do it all.
If the client really wants to write the checks they should talk to the bank they deposit their payroll withholding or just their bank if they outsource payroll. At this point I think just about everyone is required to electronically pay withholding. That however requires someone to do things like the Form 945, 1099-R with the 1096......
Since no RMD was required to be paid to the participant for 2021, no RMD would be payable to a beneficiary attributable to the 2021 distribution calendar year. The post-death RMDs must begin by 12/31 of the year following the year of the participant's death. Based on your facts, the beneficiary would need to commence RMDs by no later than 12/31/2022 with respect to the 2022 account balance.