not sure what you are asking. if they are working they will have to file their own returns to report their income. under no circumstances do their earnings get reported on your return. so the next issue is can you claim either or both of them as dependents. if so they must so indicate on their returns even if you don't actually claim them
to be a dependent they must either be a qualifying child or a qualifying relative
you can claim him/her as a qualifying child if all these tests are met:
• he/she had the same principal abode as you for more than ½ the tax year. Temporary absences like for school are ignored
• if he/she is not a full-time student, he's/she’s under 19 at the end of the tax year. If a full-time student, he's/she’s under 24 at the end of the tax year.
• he/she hasn't provided over ½ his/her own support
• he/she didn't file a joint return unless there was no tax liability but merely filing jointly to facilitate refund of taxes withheld or estimates paid
or you can claim him/her as a qualifying relative if all these tests are met:
• his/her gross income for 2020 was less than $4,300
• you provided over ½ his/her support
• he/she isn't a qualifying child of another taxpayer
