Just group by the LoadId by removing the DriverPay from the Group By statement.
So the Group By would read something like this
Group By tablename.LoadId
I am not able to test the SQL query for obvious reasons but you should get the amount you are looking for. This will pull everything into the single LoadId and not the LoadId plus the three separate DriverPay lines.
Also I did not see any SQL in your post so I cannot comment on it. It sounds like you are getting close to having what you want.
Regards,
John W.