As far as legal implications are concerned, you cannot withhold the certificates of employees except for the purpose of verification. Secondly, there may be significant loopholes in the working system that you need to address.
Considerations for Employment Terms
As someone has already mentioned, you may want to specify the minimum number of years of employment and compensation. Consider including critical termination clauses such as a minimum notice period until a replacement is found, salary withholding during final settlement, potential legal actions, and a written resignation letter outlining reasons for leaving related to the workplace.
Addressing Attrition Issues
Issues such as salary discrepancies, relationship conflicts, or workload imbalances may be contributing to the attrition rate. It's crucial to conduct a thorough analysis and work towards resolving these issues.
Wishing you good luck in addressing these challenges.