You are able to rebalance an individual Pie and you can rebalance your entire portfolio.
To rebalance an individual Pie, go to the "rebalance" button and choose "single" rebalance option, which will rebalance the selected Pie only.
To rebalance your entire portfolio, go to the "rebalance" button and choose "waterfall" option. Waterfall will rebalance all Pies within your portfolio.
Please keep in mind that any time you rebalance a Pie or your portfolio you will generally be initiating a series of buy and sell transactions. Usually every sale of a security has a tax effect which may be a gain or a loss.