It's conflicting reports regarding Dimarco. Some sourced claim it's 4.5m€ redemption for Verona and counter-redemption 6.5m€ for Inter (or around those figures). Then some sources claim it's 6m€ redemption and Inter have 50% sell-on clause, meaning we can get him for 50% sale. Also I think it depends on the player, not sure if he can block the option activation of Verona (in case we want to keep him). Or is it more beneficial for us to pay small premium to Verona for getting the plusvalenza for this season (they activate option in June, we buy him back in July with a little higher price).
As for Vanheusden, I've understood it's only gentleman agreement we get him back. We sold him for 12m€ and reports have stated the agreed price to get him back is much higher like 20m€ but I doubt it ends up being that high given Covid era and his poor injury record.