Welcome to the forum.... Hope we can help! It can be frustrating when everyone isn't contributing to the household! How long as this been going on for? Can you think of why it's happening?
Some tips would be to not use screentime as a reward for anything, encourage structured activities away from the screen eg. cooking/gardening that require sustained attention and commitment so they can't slack off and go back to the screen ( you can't leave something burning on the stove or a plant unpotted). You could also engage in a fun activity as a family like doing painting, where creative expression and teamwork is encouraged. If they want to talk about something with you, they may do it in this relaxed, non-threatening environment.
Of course, open communication is best- articulate what you expect of them and why, that way they know where they stand!
Let us know how they go,