"When the buyer and seller both sponsor a 401(k) plan, a common integration strategy is for the buyer to continue its plan for both its employees and the employees it acquires in the transaction... [T]he parties should enter into a transition services agreement outlining their rights and responsibilities during the transition period.... [T]he buyer should obtain the information necessary to fulfill ACA reporting requirements for the next year as well as the data necessary to transition the seller's former employees onto the buyer's hours tracking system for purposes of ACA's 'pay or play' employer mandate. When the seller sponsors a flexible spending account (FSA), the parties must decide whether the buyer will transmit contributions to the seller's plan for the remainder of the year or transfer the seller's employees (along with their elections and account balances) to the buyer's plan."