Nested IF Function with 3 Variables... Help!

I've created a spreadsheet to keep track of my time (clock in/clock out). I have my IF function working for all of my clocks except the days where I have three clocks.

For example... I have days where I clock in/out and then work from home and have another clock time as well. It's those days that are tripping me up.

For my regular two day times:
=IF((K6+L6)>0,(K6+L6),(E6-D6))

I just can't get that third variable working. I've tried to nest it but apparently this is smarter than me. I'm on a time crunch to get this working, too.

If anyone has any ideas or help they can throw my way, I'd be super grateful!