Melee 2 units versus 2

When 2 against 2 units have always paired them off so 2 seperate melees even if only say 5% of units on each end in contat so large overlaps on each end of combat. This means the 2 opposing units which mainly in contact with each othet aren't paired off against each other. My colleague is adamant those 2 fight each other with the other 2 counted as supports. Whose rigjt or neither of us? Thanks eric

Is this the scenario you describing below. If so your opponent is correct.

Yes thats it so I'll have to admit defeat. Wanted to show in diagram form but didn't know how. Assume its under multiple melees identifying main units. So using your diagram and extending each group to 5 units and keeping same shape would mean 4 combats with a support unit on each side. Thanks Eric

So where its 1 versus 1 with only sligjt contact thats a melee but not in cases of multiple units? Eric

It is where the main units line up that matters. One on one is always two main units.