Have had a quick read through your other thread now. There are some parts on there I agree with, and some I think will depend on Rosalie. But of course this is only my humble opinion so feel free to ignore 
So I agree that to express and carry on bf at 3 weeks, on a regular basis will be a challenge. Your supply probably won't have settled and I'd imagine Rosalie won't yet have a proper feeding routine? Plus if she has, it's highly likely to change over the next few weeks. However, this will depend on Rosalie, as per the good old saying of every baby is different. 
The other thing is trying to fit in expressing in between feeds. If Rosalie's still feeding very frequently, you might struggle with this. Also, missing the feed that you'll replace with a bottle, will probably make you sore for a bit.
Agreed that although Rosalie won't know DH very well yet, that's not to say she won't be more than happy to take a bottle from him. DS would take milk from DH and pretty much anyone - he loved his milk 
So early on, there's also a risk of nipple confusion, although if you're still using the shields, this may help prevent that anyway. Apparently, this is because babies use a different technique to get milk from a breast vs bottle.
Personally, I'd be very reluctant to express a regular bottle with her being so young, but I would think about trying to express a little bit in a couple of weeks. Just to see a) if she will take a bottle and b) how you get on with expressing.
Oops - that was really long
And as I said, do ignore if you think I'm talking rubbish 