Combo Chart with Multiple Lines

Afternoon, 

I am trying to create a few reports for a client to replace their existing reports. One of their current reports is a combo chart that utilizes three parameters: Entity, Comparative Entities, Year(s). Their current column values are a few basic values such as Net Income and Return on Net Assets. The combo chart has two Line Values one for the entity cumulative amount and comparative entity cumulative amounts. The entity cumulative amount line value is tied to the Entity parameter and the comparative entity cumulative amounts are tied to the Comparative Entities parameter. Then it is filtered by year. 

My question is how can I have my current combo chart have two line values? One tied to entity cumulative amounts for Entity and the second tied to comparative entity cumulative amounts for Comparative Entities. I need each parameter to be able to create their own line value for the column chart and to allow the user to select multiple entities on run time. 

I am new to PowerBI and any assistance would be much appreciated.