Two companies that both use Lacerte - Simply use backup from the company that is going away and restore onto the company that is absorbing. My experience (which predates fast path) is that there will two different numbers in Firm Number data in screen 1. The old firm data will print one page 2 of the 1040 for those old returns. You should contact customer support to affirm this information and they can likely give you more info on how to merge.