Sold option is great but...

if i have a quantity of lets say 50 pikachus that i paid $50 for, and i sold 1 of them for $5.  I should be able to go into that and deduct 1 pikachu from the 50.  Instead i have to remove 1 from it, then add 1 on its own, then go and put in the sale.  Can this be optimized to allow 1 of the original position of 50 to be counted as sold?