Options for retaining a CRITICAL employee

Hello SearchFunders,

I have an interesting deal on my plate. We're located in Canada to give some context. It's a commercial equipment repair business (leaving out detail here for the sake of anonymity). Margins are quite good and there is significant growth potential. It's a family business, wherein a husband/wife own the business. Their son, in his 30s, acts as the main repair/service tech.

My first thought: "well, why doesn't junior take a loan and pay back mom and dad with the significant SDE?"

Apparently he financially can't or doesn't want to buy the business, but wants to stay and carry on a career as the technician. That somewhat baffles me, but I don't know his motivations either.

Options on mitigating the retention risk if I were to pursue the deal:

A) non-compete (my thought is that this is the weakest option)
B) partner with him to buy the business
C) long-term incentive plan
D) partner with another similar business to acquire (work with someone else who has incentive + skillset)
E) put an earn-out clause on the sellers (this, I suppose, isn't mutually exclusive with the other options)
F) run for the hills and find another deal!

Thoughts and ideas are welcome and appreciated!