Yes, it can be done. All you need to do is bind the Tag Pens dataset property of the Easy Chart to a cell update binding. The cell update binding allows you to dynamically change a cells values in a dataset. If you look at the Tag Pens dataset you will see that the second column is the tag path. In the cell update binding select the tag path cell you want to change and press the green + button to add it below. Select the added record and set the value to whatever path you want. To use a property or tag value use the links on the right hand side. So for example you the value can be:
Pumps{Root Container.PumpNumber}/Flow
You can also just use a property reference for the entire path:
{Root Container.FlowTagPath}
Let me know if you have any questions.