You should create e.g. 2 new series, define data for them and define new stack:
Please note that "default" stack is also used by the candlestick series if you haven't defined it otherwise, that's why create a new stack:
When defining those new series, set stack to "myNewStack":
//change data index or source for each of those new series:
If you have already tried that, please provide your example so that we can see what is not working for you and investigate the cause of the problem.