How to make multiple datatype for attribute ?

Hi CUBA Team,
I have an issue: In my application, I have 3 entities like categories: Customer, Employer,Department
And 2 entities like documents

  1.  “CashReceipt” with attribute : “CashPayer”
  2.  “BankReceipt” with attribute : “BankPayer”
  3.  1.    “CashPayer” related to Customer type, Employer type and  String type.
  4.  2.    “BankPayer” related Customer type, Employer type and  Department type.

You can see sample in attachments images.

I see you have an example :
But it’s not help to resolve my problem. Because I can not make one entity inheritancefrom 2 or more difference entities at one time.
How I can make this model inCuba-Platform?