My child (a dependent) received a K-1 as they were a beneficiary from an estate. How do I add this to my tax return?

You don't ... if the child is required to file a return it goes on their return only.

The Schedule K-1 is entered on the dependent's tax return since they received the income from the estate as a beneficiary.

How much taxable income is involved? Depending on amount and kind of income, no return may be required ...