What is the ruling on combining two valid sale items for a single price when the price can be apportioned by parts?

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When both sold items allow for the price to be apportioned by parts (e.g., a share of a jointly owned slave sold without the partner's permission, or two measures from a single heap of grain where only a fraction is owned), there are two views. One view states the sale is valid for the portion owned by the seller, apportioning the price accordingly, and void for the portion not owned. This is the position held by Malik, Abu Hanifa, and one opinion of Al-Shafi'i. The evidence supporting this view is that each item has an independent legal status, and since the portion owned is validly sold by its rightful owner, it should stand independently, analogous to selling a plot of land and a sword together. The second view holds that the entire transaction is void in both portions. This is held by Ahmad (in one narration), Abu Thur, and another opinion of Al-Shafi'i, based on the principle that mixing the lawful and unlawful causes the prohibition to prevail, or that if the contract cannot be validated for everything agreed upon, it is void in its entirety, similar to combining the sale of two sisters or exchanging one dirham for two.