Defining Field Relationships
You establish the field relationships between the project and the SAP system.
The source fields and the structure relationships between the project and the SAP system must have been defined.
...
1.
From the list
of steps, choose Maintain Field Mapping and Conversion
Rules.
A screen appears.
2. Choose Change.
3. Position the cursor on the appropriate SAP field.
4.
Choose Assign source field.
The Assign source field dialog box appears.
5.
Select the
corresponding source field.
The system displays this field as source field now and defaults a
field-related 1:1 processing (Move) of data.

You can assign multiple source fields to an SAP field. However, data can only be processed by means of a rule that you create yourself. The predefined rules only support 1:1 relationships.