On post-merger integration teams that I’ve been on with the highest degree of effectiveness have had HR leadership engaged throughout the entire deal process, particularly in Due Diligence and the development of Terms (especially in the area of synergies which, typically, involve expected process efficiencies that impact people).
In these cases, the value delivered by HR included keeping the Acquiring entity’s leadership honest about its own capabilities (both process and people) throughout the entire M&A process, allowing for the development of an effective post-merger plan before Day One that included what functions to integrate immediately, what others to integrate over time (based on change management needs and readiness), and even functions to keep intact (e.g. if R&D is not a core competency of the Acquirer and is required for the value defined by the deal to be realized).
