We absolutely bribed her with mini ice creams if she poops. Worked great and she quickly learned to poop on the potty. Took maybe 3 days to cement the idea so 3 mini ice creams. Then I bought a pack of cheap mini animals and let her pick one every time she poops to slowly build a zoo. Also every time she poops on the potty we made a big deal out of it clapping and cheering her up and she loved it. My MIL and SILs even asked to FaceTime them every time she does it so that they can cheer her up and to give her stimulation to do it.
Our potty pooping is very hit and miss, he normally does it in his nappy at bedtime, which is not ideal! But today, I went upstairs to put the baby down for a nap and I could here him shout poo poo, and he had gone on the potty all by himself 😳 and was bent over waiting for me to wipe 😂
Find something that will keep her preoccupied on the toilet to let her be comfortable sitting there for a few minutes longer. We used bubbles, she would sit there and be allowed to blow bubbles and the action of blowing would squeeze her tummy and encourage her to go (both wees and poos).