Is it possible to choose a member dynamically based on another member selection?

Summary:

We have users a number of use cases where we'd like to select a member in a report based on another member selection. For example we have a view dimension which allows users to select between MTD and YTD numbers (these selections show both revenue and expenses as positive numbers). We also have MTD_Signed and a YTD_Signed members which allows users to run reports with the signage for revenue as positive and expenses shown as negative. Within the main report we show both MTD and YTD number in different columns. We'd like to expose the