Hi Ray
Not sure if I understood your comment. If you have a number of securities you can only change the value. If you buy 100 items at a price of 30 and next day the price is 28 you can calculate the loss. If the price is higher you get a profit. The underlying can only be changed by a sale. There is no adjustment in the item number.
If there is a change due to a corporate action you can use the coportate action. This means that you have currently 100 items but they are new now only 50 items because there is capital reduction this can be done. The value of the items should then double.
Kind regards
Juerg Heiz