As long as she seems to be committed when she's forced to sit, thats a good sign.
Though I have had quite the fiasco with a bad broody duck. Long story short, I knew nothing about broody ducks at the time, (this situation is actually what made me join) and let 4 ducks share a nest. They fought over the eggs, and broke a lot of eggs that had fully formed ducklings in them. I would find kicked out broken eggs, with full babies in them.
They messed up the humidity because of fighting, and kept retrying for more babies every time the babies didn't hatch.
Like I said, I knew nothing about broody ducks so I can't believe I let them sit that long, but, I did, eventually I joined, and I made them quit brooding. My Mallard who had originally started the nest decided to sit again, I made her a separate area by putting a baby gate around her nesting site. She hatched 3 beautiful babies.
I would prepare for her to quit, or not be committed enough to be able to keep the eggs at proper humidity/temperature during lockdown.
I would build, or buy an incubator, and try to candle at least a few of the eggs before day 18, but all of them if possible so you can toss bad ones. Just be prepared to intervene if you have to.