to remove the synthetic key you can rename the fields...
or you can create the composite key.. it depends on your data model
here you want all the data from partnership table rt?
PartnerID & CompanyID as key,
PartnerID & CompanyID as key
... if i that not works then post some sample data.
Synthetic key :-- When between two table 2 or more than 2 fields are common, then Synthetic key are made.
there are three ways to remove Synthetic key.
3) Allias (that is rename the fields)
On the basis of these above , you can made the best modelling.