keeping Purchases after merge
i had some items that i didn't want anymore and i wanted to merge them together to have more sku space in my item lists . but was surprised when you merge items together it disappear from purchase invoice and modify the amount of purchase invoices which will change your books dramatically and will miss up all the work you done in the past . also will miss up your vendor accounts and you will be 100% lost in accounting and records !
i would suggest you allow merge or delet of items without affecting posted purchase orders and posted sales orders as their are very important for book keeping .
im using Microsoft dynamics for my other business , and soon as you post your purchase order and sales order no body will be able to delet or modify them no matter what even if you delet all item list ! purchase and sales wont be affected by this , there are other ways to modify them for example by inventory adjustment or return or .... ,