Check with your CPA again.

You are supposed to net Lines 7, 8a, 8b, and 8c on Line 3g.

So when it says "enter losses in Part III",  then that means if the total summation of all lines (7, 8a, 8b, and 8c), is less than zero, enter that value in Part III. Otherwise Part I. ?

Yes, I believe that to be the case. 

I will page @Rick19744 on this. Form 7203 is a new form.

An AMBIGUOUS one at that!!!

I agree with @tagteam .

Each of the lines noted request detail on capital gains or losses which should be a net figure; and each respective line states "net".

The K-1 is prepared correctly as those figures will be reported separately for purposes of determining your taxable income.

The form 7203 is determining your net basis which has a different purpose.