Employer Merged Its Underfunded Single Employer Plan into a Multiemployer Plan and Later Withdrew -- In Calculating Its Withdrawal Liability, Should the Employer's Payment of the Underfunded Portion Be Treated As an Employer Contribution?

In case my previous post was too confusing, please allow me to replace it with the following:

I represent a multiemployer defined benefit plan. Employer X previously maintained a single employer defined benefit plan for its collectively bargained employees. X negotiated the merger of its plan into the multiemployer plan in 2005. Under the merger agreement between the union covering X's employees and X, X agreed to make contributions for the underfunded portion of its single employer plan to the multiemployer plan over a 10-year period with interest. Instead, X paid the entire underfunded portion plus interest to the multiemployer plan in a lump sum in 2006.  X withdrew from the plan in 2019. In assessing X for withdrawal liability, the actuary treated the lump sum contribution to the plan as an employer contribution in determining the amount of X's withdrawal liability. X has filed a request for review of the fund's assessment challenging the treatment of the lump sum contribution as an employer contribution. Did the actuary correctly characterize the payment as an employer contribution?

I thought your first post was clear.  I am closing this thread to avoid double posting.