One Employer - 2 Plans?

Ran into a situation where an employer has an existing profit sharing only plan that holds essentially only employer stock.  The company is wanting to add a separate 401k plan to allow their employees to defer their own funds for retirement.  I'm thinking that having 2 separate plans won't work and that their only option is to amend the existing profit sharing plan to allow for 401k contributions.  Am I overthinking this?  Anyone have any ideas on how to do this in the simplest way possible?

It could work, but they don't need two plans.

Just add 401(k) to the PSP.  Structure it so that the participation have investment direction over deferrals and the ER had direction over ER funds.

Agree with BG, but there's also no reason they can't have two plans.

Agree with both of the above. There might be good reasons to have 2 plans but it can also be accomplished in 1 plan.

If you have two plans and combined they are Top Heavy, make sure that the plan documents agree as to which plan gets the TH contribution.

I'm recalling that if the company pays dividends and you set up a K-SOP, the dividends are deductible under IRC 404(k). Another plus which might apply.