Data Modeling and Relationships

Hi,

I am experiencing an issue with my data modeling and relationships, see description below:

• I am currently working with four types of files 2018 Sales, 2018 Credit, 2017 Sales, 207 Credit
• I created relationships between the four files, with 2018 Sales as the leading file – 2018 Sales connected to 2018 Credit 7 2017 Sales, 2017 Sales connected to 2017 Credit
• My Net Sales, GP and other calculations, where don on my Sales file
• Net Sales = 2018 Sales column - 2018 Credit column
• When we look at the results the numbers came incorrectly so we started to debug the issue, what we found was as follow –
• When I choose the customers to be pointed from the 2018 Sales sheet I see my customer MM and his sales number as XX
• When I choose the customers to be pointed from the 2018 Sales sheet and the credit from 2018 Credit sheet I see a list of 10 additional customers with the total of YY, which is the exact number our calculation was off.
• When I choose the customers to be pointed from the 2018 Credit sheet I see the correct number as far as credit but now my sales show ten additional customers and their total is incorrect

I assume the issue comes from the relationship creation but I could not understand how to fix it, any suggestions?