This is an approach you can use that will help reduce any confusion

Pull out the list you are working with

Check in the plan item add / modify section if the plan you need exists - if it does not then add the plan in. If you see a plan that you could use but needs a minor modification in the name then do it now.

Now search all the plan items category wise and

Inactivate the plans you do not want ; Set the plan as weight / species specific if needed ; set the price, volume discount and weight surcharge for the plan if applicable ; now set the reminder, flag to show in past services and substance logs

Create Groups for plans that point to common stock

Add "Stock without PO" in hand that you need to reflect manufacturer name , lot id and expiry date

Create Wellness Packs and Packaged Plan Groups

If you wish to implement the Purchase order process of ordering stock then you need to link the plan to the inventory / vendor items (after you have added the vendor items of your distributer)