You cannot make a risk-free investment in a PRO Trader, because risk-free investments option is available only for the newbies who are learning how to use the FBS CopyTrade application.
If you made a risk-free investment in a Trader before he/she has become a PRO, and the Trader has become a PRO in the course of the investment, the investment will not be closed, and you will be able to finish it as usual.