I can't win

Why is it when one kid is sleeping the other one is either awake or trying their darndest to wake the other one up? it's gotta be an addendum to murphy's law....a child who is sleeping will not stay sleeping due to sibling.
A little explanation. Lily has been TERRIBLE at going to sleep lately. If she naps, it's late in the day and then she's up till 10 or after. If she doesn't nap she's usually up until 9 or 10 anyway. Not that I dont' try to get her to go down at 8:30 or so. She is just very consistent and insistent that she will not lay down unless I stay in there. So as not to create a bad habit, I rub her back for a few minutes, kiss, goodnight, leave the room, Lily comes out of room teary-eyed, "don't leave me....", Repeat, repeat, repeat. FRUSTRATION!
Zoe has actually been a great sleeper almost since she's been born, but lately she has been crying her guts out when I leave the room. It will taper off for a few days and then come on strong again. And lately they are both booger-ridden which doesn't help. We actually thought Zoe had an ear infection yesterday, took her to the doctor, no ear infection just a cold. But she is so not like herself. She's usually a pretty happy, mild baby, but yesterday and today she's had these crying fits where nothing will appease her. I'm guessing it's teething although she never acted this way with any of the other 8 teeth she's already gotten. sigh.
So tonight I was stoked because Lily didn't take a nap and I was praying for an 8:00 bedtime for them both. Even better I got Zoe to go down calmly and quickly at 7:30! So 8:00 rolls around, routine is done, Lily in bed, rubbing her back. Then Lily says something out loud. Zoe wakes up (why are they sharing a room again?). So I get up from Lily's bed to lay Zoe back down, Zoe is going back to sleep....Lily gets up, loudly says, 'what are you doing, mom?' and Zoe pops up screaming. ARGHHH!!
I lay Lily down sternly, say be quiet, rub her back while Zoe cries and miraculously a tired Lily falls asleep. Then it's out of the crib to clean up a very snotty and slobbery Zoe. But she won't lay back down without freaking out now. So I've now been holding her on my lap while she chews on the top of the squeezable syringe that comes with the infants tylenol. (good for teething?) So what started out as an optimistic 8:00 bedtime, short and sweet, turned into the usual hour plus bedtime saga at our house.
And while my husband sits in his cop car listening to the Jazz game on a quiet night when even the druggies and transients won't come out, he tells me that it's really me who has the easy job...
You be the judge! :o)