Question on Employee NDA's

Scenario:
- Post-LOI and running diligence on a firm with ~150 employees.
- Ownership, CEO, COO, and CFO are all involved and communication is solid.
- Both sides wish to keep news of the transaction on a need-to-know basis until closing.
- Two years ago they migrated to a cloud-based system. We need to access their old servers to complete an industry-specific audit.
- The IT department is needed to access the old data/ servers.

Would like to know if people have had select employees sign NDA's during diligence? If so, were there any additional terms/ clauses specific to the employee(s) you deemed critical, that went above and beyond the standardized NDA language?

Any feedback - no matter the scenario - would be very helpful. Thank you!