Note, there are rules that limit the aggregation of safe harbor plans with other plans for coverage and nondiscrimination testing. In all likelihood, you will need to meet coverage in the two SH plans separately for 2025 (i.e., as if both plans excluded all other employees). Also, check the plans to make sure that they don't cover the other entities by their terms. You could have some people being covered accidentally in more than one plan. Last but not least, there are rules about modifying safe harbor plans mid-year. These rules may prevent you from merging anytime other than the first day of plan year. So, in other words, therre is a lot to think about here. Consider legal counsel (regardless of whether it's me or someone else). M&A is complex and shouldn't be handled without knowledgeable advice, IMO.