SAC modelling - field mappings and measures

[JBARLOW]

Hi all,  just after some guidance on the best approach to model data from different sources in SAC.
For example:
Datasource 1 contains:   User ID , Job Title , Department
Datasource 2 contains:    User ID, First name, Last Name
If I create a new model starting with data and pick say source 1 .. when I then try and add
source 2 I'm unable to as of course First name & Last name cannot be mapped to anything.

Option 2 is I create a new model with no data and manually create dimensions for both Sources above,
However SAC forces you to create a measure before allowing you to save and add data......  but as there is no measure in either data source - the mapping also fails so I can't import the data..........

Or am I missing something obvious?
Once the data is in the model in its entirety - that's when I want to create measures

Edit - Just for context / clarity the data i'm working with is Success Factors,  hence the need for mutiple queries in SAC as I need data from different tables in SF......