Oh bah to the ongoing feverishness, CP! Hope whatever it is departs sharpish.
I think you're right about the pleading/nagging/yelling/giving in situation. I think once I've demonstrated to DD that I WILL follow through with what I say - whether it's yes/no/later etc. - then she tends to be better behaved (assuming illness/tiredness/needing a poo etc. is out of the equation!)
This week I've mostly been on my own (while DH is at work) with both DC and generally, it's been okay, although there are pressured moments. I think I'd be more of a wreck if DS didn't nap as prodigiously as he does. And he's now showing signs of being able to be left for short periods with something to look at while awake without fussing, which means I can do things without having to have him in the sling or under one arm during wakeful periods.
This is also why I'm clamping down on DD - I've realised once there are two DC to deal with, I don't have the luxury of time and patience to work through every toddler issue with DD. She's got to learn that she has to just shut up and get on with it sometimes - or wait while Mummy gets on with it!
I feel slightly hypocritical that I get cross at DD for nagging me to do something and refusing to wait for anything when I also get cross when she doesn't do what I ask her reasonably sharpish. She does the "Let me just....I've GOT to do this first...." etc. when I want her to do something and she's absolutely echoing me.
But tough luck, I happen to be higher up in the pecking order than her (with a small baby's needs to consider too) so I'm dealing with that by telling her "Mummy's the boss!" as an explanation for this double standard...! 