"Expand" function on WMS picking

We have quite a few products that create assemblies through sales orders. They go to ‘backorder’ on approval of the SO, then when on the WMS pick screen, it lists out all the components. Trouble is, if there are two assemblies listing out all the components, then the picker has no idea which products should be selected together. I believe there is an ‘Expand’ function where you can see the finalised product, then select ‘Expand’ to see the components. We are using the basic function of the WMS as the Advanced was not suitable for us. However, I would see this function as something that is basic. The picker should know what they are picking in the first instance, then be able to drill down to the individual components. Otherwise, the customer is not going to get what they ordered!