Retaining key employees and socio cultural impact on transactions

Given much of the focus on transactions revolves around the financial picture. There is an every growing importance when studying successful M&A deals around how employees from the buyer and target are handled. Thinking specifically about how you review the importance of retention of key employees, and payments and contracts structured to support the employee needs during the time of transition, as well as improved diligence work can be done early on (pre-close) to better understand and capture any nuances in culture, values and human capital needs to help improve success. Curious to ways you may have been able to overcome the retention and cultural fit issues.