Is an amendment to each plan document necessary to merge 2 DC plans in

[John A]

An employer has a frozen money purchase plan. The employer starts a 401(k) plan and uses one trust for both the money purchase plan assets and the 401(k) plan assets. There is a section in the 401(k) plan covering how to treat frozen money purchase plan assets. If this section is used, are the plans merged automatically with no further action? Does there have to be a specific amendment to each plan document stating that the plans have been merged? Other than meeting the 414l requirements, what action is necessary to merge the plans?