I see that you cannot share your data, but it will be really exciting to help you out if you can share the schema of your data.
That will provide a better understanding into your problem.
Well, it's nothing dramatic
A normal table of transactions with the following columns (every transaction is a separate record):
Member ID, Transaction Value, Retailer Name, Transaction Date
is there anything unclear about this one? I just wanna make this in a quick filter so I can change the retailers from a drop-down and also change the period of research.
You can create a dynamic set by using calculated field.If I would have seen your data would have helped better but just to give you an idea so that you can implement in your analysis.
Eg: Scenario here is I want to create a dynamic set to display top 20 customers by profit and rest as Others
First create a group using Top tab by using profit for 20 customers
Then create a calculated field : "Customer Profit Bin"
If [Top 20 by Profit] = true then [Customer Name]