apply in connection with a plan amendment under section 439(a)(5)(C), regarding conditional benefit modifications. (f) Treatment of plan amendments For purposes of this section— (1) if two or more plan amendments increasing benefits or establishing new benefits are adopted in a plan year, such amendments shall be treated as a single amendment adopted on the last day of the plan year, (2) all benefit increases and new benefits adopted in a single amendment are treated as a single benefit increase, irrespective of whether the increases and new benefits take effect in more than one plan year, and (3) increases in contributions or decreases in plan liabilities which are scheduled to take effect in future plan years may be taken into account in connection with a plan amendment if they have been agreed to in writing or otherwise formalized by the date the plan amendment is adopted. 440A. Composite plan restrictions to preserve legacy plan funding (a) Treatment as a legacy plan (1) In general For purposes of this subchapter, a defined benefit plan shall be treated as a legacy plan with respect to the composite plan under which the employees who were eligible to accrue a benefit under the defined benefit plan become eligible to accrue a benefit under such composite plan. (2) Component plans In any case in which a defined benefit plan is amended to add a composite plan component pursuant to section 437(b), paragraph (1) shall be applied by substituting defined benefit component for defined benefit plan and composite plan component for composite plan . (3) Eligible to accrue a benefit For purposes of paragraph (1), an employee is considered eligible to accrue a benefit under a composite plan as of the first day in which the employee completes an hour of service under a collective bargaining agreement that provides for contributions to and accruals under the composite plan in lieu of accruals under the legacy plan. (4) Collective bargaining agreement As used in this subpart, the term collective bargaining agreement