If you can take the next three weeks to study the times they typically use the diaper & have them sit on the potties within those windows. For example the 1yr old always pees atleast twice around 9 AM because when I arrive by 9:30 she has a full diaper. Way bigger than her normal 1 time so I can tell she goes multiple times. So Id put her on the pot between 8:55- 9:20 with a game or something she can focus on.
Cute stickers on the potty too helps, music if they like that, & if they are tv watching kids you can use that to your advantage to keep focus. Don’t give up tho be consistent & try your best to remain calm because that teaches its safe to continue learning. Making a game or song out of it too teach them to communicate more often they have to pee.
Patience! There might be a lot of accidents, and it can be frustrating but just be patient with them, reassure them. Rewards are great, sticker charts etc. and just stick to it!