The way I would do that would probably be to set up two surveys. One survey for the employee only and in which the last question asks for the manager's email address. The second survey would have the manager questions. And you could set up an action in the first survey to trigger the second survey to send an invitation to the email address provided in that last question. You would need to pass all responses and embedded data fields from the first survey as new embedded data fields in the second survey, so that would take a minute, but that seems easiest to me in the long run.

I'm looking at doing something similar to Megan above but with more sections that require input from people in different roles. I am working in education and want to create a survey that collects assessment data from different educators but on the same survey so that all the data is available for me on my end. Would anyone know the most feasible/efficient way to do this? Preferably I would like to send a follow up survey for post intervention data at the end of the school year. Any ideas would be appreciated.
Thanks!