Who's The Employer?

Insurance company has agents that are 1099 contract employees..  These 1099Agents are not covered by the Insurance Agency's 401k plan nor other benefits of the insurance company and want to start their own 401k plans.  The 1099agents also lease employees from the Insurance Agency that are licensed employees.  The agent has control over these employees daily activities but ultimately the right to fire or hire the actual employees is really up to the larger insurance company. 

Trying to determine if the employees that are leased to the agents should or should not be included in the plan and what questions I'm forgetting to ask!   

So each agent is a self-employed contractor. I suspect the group has some control on daily leased employee activity but any one agent most likely does not. Also, that employees are employed by the insurance company and not a PEO/employee leasing company leads me to conclude they are (still) considered employees of the insurance company.

The alternative - you have a group of shared employees among a number of different self-employed agents which would be extremely messy. And in first paragraph you say agents want their own plans but then ask if these others should be included in the plan. Each presents a different premise - individual 401(k) plans or a multiple employer plan.