Is there a way to lock a specific lot of an item for a specific client while still allowing supply f

Currently, we manually block entire lots, and each time we need to sell to a client, we must unlock the lot, create the sales order (SO), and then lock it again. This process occasionally causes issues.

I am looking for a solution that allows us to lock a specific lot of an item for a specific client while still allowing supply from other available lots. If no other lots are available, the client would need to wait for the next production batch.