Hello, I went a little further from my issue : https://sprykercommunity.slack.com/archives/CKJRJM5FG/p1688368095312339 So, what I did wrong : I need to assign every business Unit to each merchant relation. But, i should not need assign any product (cause the doc says if we assign no product, all are). I'm doubtful about a spryker which doesn't work as i expect: vendor/spryker/merchant-relationship-sales-order-threshold/src/Spryker/Zed/MerchantRelationshipSalesOrderThreshold/Business/MerchantRelationshipThreshold/MerchantRelationshipThresholdReader.php::isMerchantRelationshipItem() which in my case is always false, cause I have null at $itemTransfer->getPriceProduct()->getPriceDimension()->getIdMerchantRelationship(). here's the method:

protected function isMerchantRelationshipItem(ItemTransfer $itemTransfer): bool
    {
        return $itemTransfer->getPriceProduct() &&
            $itemTransfer->getPriceProduct()->getPriceDimension() &&
            $itemTransfer->getPriceProduct()->getPriceDimension()->getIdMerchantRelationship();
    }

It should be fine if i can understand better what's happening here, if you have a link to some consistent documentation, I can deal with. Have a great evening.