Hi Rob,
Thanks for raising this on the community! Yes, you absolutely can have Breww auto-assign all ingredients; it is just down to how the recipe is set up. Within a recipe, it is the stages that define whether ingredients are auto-assigned. When adding a stage to a recipe, you can choose whether the stock can be auto-allocated for this stage when starting the batch and whether the stock can be pre-allocated to this stage. As long as the auto allocation box is checked, any ingredient additions in that stage can be auto-allocated when starting the batch.
We do have some more information on recipes in our 📘 Introduction to production guide, too, which you might find helpful.