Sweet lew -
Please clarify the nature of those entities interms of Raw or Inprocess or manufacturing additives/agents (not necessarily an ingredient)
If they are Raw or Inprocess have you pontentially identified their respective risk profile. Should they be of high risk or where you have had a good history of micro hits, its certainly worth while considering additional tanks/silos to manage the clean break situation.
Another worthwhile exercise would be to come up with a matrix of Entity: Product usage & cost analysis based on ingredient costs, quantity & micro/contaminant risk profile that would relate to Product recall. Based on which you can justify the need or the lack there of for additional tanks/silos. This would also help agree upon & come up with the Brackets for traceability/ recall situation.
Along the same lines you can get away with the low risk / no risk agents/additive the way you are handling them right now, as long as you are Ok with bracketing for a longer time frame & more products should you ever get into a recall situation.
Having said the above, if you have for stock rotation (monitoring) purpose alone, what are your current practices around acceptance of a incoming lot. Do you have weighing scales, tank marks/dip scales etc., that you currently use to verify/document the current stock & then fill up with the new lot ? If you do, that can be use in my guess to an extent. Points to remember is also to have a system in place for FIFO or FEFO when the same entity/commodity is stored in multiple Silos/tanks as well. That could further complicate the matter if such a system of documenting the current levels & incoming load dumping & usage decisions.
Hopefully this helped rather confuse your dilemma further.