Our little one goes through phases where she notices when she goes and then she won't for a day. But we're moving forward. I also have a 6 month old so I can totally sympathize with your daily juggle :)
What has been working for us is this:
We had her run around kind of nakey-butt for a few days and put her on the potty at specific times during the day. Right away in the morning, after breakfast, after lunch, before dinner, and right before bed, taking mental notes when she would actually go. Initially we had a few misses but I tried to keep her in an easy-to-clean-up area to play.
Now I know that she'll have a big pee right at getting up (I've also noticed that when she gets up in the middle of the night and talks to herself she's actually peeing in her diaper - so she doesn't really pee in her sleep) another pee at around 9am, one after lunch and one after her afternoon nap. So I'll put her in undies or in a cloth dipe if I'm really busy, but just give her opportunities to use the potty at regular intervals. We talk about being "dry" a lot and she helps wipe up any accidents.
You'll be able to pick up on her pee patterns pretty quick. Then just give her opportunities to be successful on the potty and reward them! So it might seem like "mommy training" for a little bit, but she'll be able to draw the connection between peepee and pee goes IN the potty. And I don't know about you but we can tell when there's a poopy coming (lots of faces and standing really still) so we pop her on the pot for that too.
Sometimes the patterns are weird, for awhile she'd go potty a little and then go again 10 minutes later and again 10 min after that. That can try the patience. It's worked for us to have her sit on the little potty and scoot around or just plop on a 20 min cartoon while she sits there to wait it out. That way I have time with the baby.
It might take a little while to figure out what will work for you and what will motivate her (treats, stickers, a show) to stay on the potty. But in the mean time best of luck. Having those two little ones is a handful but is such a blessing as well.
-Krys