@HLlalo & @Snakedog116, FYI, the Reliable Presence Smart App doesn’t actually do what you describe in these posts. The intent of that app is to make a single person’s presence more reliable so that you can identify yourself with multiple presence sensors and your presence will be triggered as away if any of them leave. This means that if you try to use it by combining the presence sensors of yourself and your partner, it will trigger as away when either of you leave home, even if the other is still at home. This is exactly opposite of what I wanted, since my use case was exactly like yours - I wanted to trigger my ecobee3 to the “Away” Comfort Mode via IFTTT only when everyone was gone.
I ended up taking the Reliable Presence SmartApp and modifying it to do what I wanted, which is to combine the presence sensors of my wife and me so that it will trigger as away only when both of us are gone, and will trigger as home when either of us is home. Works like a charm. Only after I did this did I realize that someone else had already done it, so I’ll link to that one by @baldeagle072: Everyone’s Presence