Millisecond Forums

First, I have a "store" that has categories of items, "category A", category "B", etc. For example, people may click "category A", and they are presented with items in "category A." Then, they click item 1, and then they are presented with a buying trial A or B. So far, I have the store as a trial, which branches to another trial for the items in the category. I am having trouble with the last part because I can't figure out how to branch into one of the buying trials (which should be a random selection of either A or B). Also, once they buy the product, I need to have a counting mechanism that subtracts the amount they bought from a set amount (much like a shopping cart). They should be able to go back to the store and repeat this process in which the counting mechanism should make calculations across the trials. Would these things be possible to do in Inquisit?