I'm not sure I understand the question, but two things that may help are (1) you can subscribe to an asset and then use listassettransactions to obtain the most recent transactions for that asset, (2) because assets are fungible, MultiChain does not track the particular issuer of a particular unit of an asset, if that asset has undergone multiple issuances.
In MultiChain 2.0 (alphas) you could use inline metadata and transaction filters to propagate this information from the asset issuance to subsequent transactions, but this would require more complex transaction building logic, and you'd also have to consider what to do if two quantities of the asset with different metadata are mixed together in a transaction.
Is there any reason why you can't just use a different assets for each origin you want to track?