Seller Financing or Minority Roll-over equity by the Seller

Hello,

In case of (small/medium) businesses dependent on the seller (or a key shareholder) - for customers/sales channels or supplier engagements etc,

To secure financial & contribution commitments from the seller,
What is more advisable in your experience ?
- Seller Financing, or
- Minority Roll-over equity

What could be recommended T&Cs for such ?

This is for acquisition in auto-parts company (in Europe) turnover about ยง4 million (EBIT 15%)