What my balance would be if i had ...

Part of being a good investor is trying to learn from the past. It would be great if there was some way to look back at my decisions, and project forward to what the balance would be now. For example, i sold three stocks not long ago and used the proceeds to added to an existing position, i think im ahead on the switch, but its hard to work out. I dont know the best way to do that from a UI perspective, but a feature like that would definetly be useful for self awareness of past decisions, and self improvment. Thanks