First, you never combine income with your own, each child must file their own tax return for their own name. If filing online, each account can only file one return for one person. You would need to set up separate turbotax accounts for each child. Or, purchase Turbotax on a CD or download to install on your own Mac or PC, and you can file multiple returns from one computer (each return is a separate data file like a spreadsheet or word processor file).
A 1099-NEC is usually issued when someone is self-employed or an independent contractor. This would require filing a tax return that includes a schedule C and schedule SE. They report all their self-employment income (including income from customers or clients that was not reported on a 1099), they can deduct ordinary and necessary work expenses (assuming they have accurate records to support the expenses) and they pay income tax and self-employment tax on the net profit.
However, let's make sure they really are self-employed. Sometimes, payers use the wrong forms. What did your daughters actually do to receive the money that was reported on the 1099s?
