Hi there!

All modifiers are cumulative. So in this case, the flanking unit would be Flanking and Pinching.

And in fact Pinching can be cumulative! If two units are pinching, each units gets (+0)+1/+1. For every extra unit (on a new side), all units get an extra (+0)+1/+1!

So if Unit A is on the left flank, Unit B is on the front, and Unit C is on the right flank, all three of them get (+0)+2/+2 for pinching.

Then Unit A and Unit C would get the bonus for Flanking, so they'd get (+0)+3/+2.