In order to force records in an ADU to be treated as Individual records, you need to do the following:
 
1.  Add the Account_Type field to the UL_Accounts section of the PB4 Control file.  For example:
 
a.  If you want every record in the ADU to be treated as an Individual:
 
,account_type                    CONSTANT 'IN'
Or
 
b.  If you only want only certain records treated as an Individual:
 
,account_type                    POSITION(6982:6983) CHAR
 
2.  If you chose 1b, then you must add ‘IN’, in a 2 character column of your choosing in the ADU file (the example above used POSITION(6982:6983)).
3.  As explained in the Help page below, update the Account Category Matching Rule Attribute to "Consider Account Category" in the Account Data Upload Vendor File Code screen for that Vendor code.

https://www.blackbaud.com/files/support/guides/ta5/Iectv36/Setting_Attributes_for_an_Account_Data_Upload_Vendor_File_Code.htm