I'm working with a company starting a 401(k) plan. The company was formed as a result of the merger of Spin-off A and Spin-off B.

Spin-off A had company stock in the 401(k) Plan -- closed to new money. However, as a result of this transaction, 10% of the Spin-off A shares will become Company C shares. Within the new Company C 401(k) plan, there will be two separate stock accounts: Spin-off A balances and Company C balances (both will be closed to new money - and all stock money can be traded out to core funds immediately).

What admin/compliance issues do I need to consider to implement this change?