Once the return is sent - it's like dropping it in the mailbox, it can't be taken back. But, you can amend a tax return to include the information. (I'm assuming you need to amend because a health care penalty was assessed.)
The Form 1040X (amendment form) will not be ready until 1/31/19 but TurboTax will walk you through the amendment process and I have included a link below that will help you get started. However, you are going to want to wait until you have actually received your first refund before you start the amendment (this is the advice that the IRS gives). This is because if there are any other issues in your return or forms that come up while the IRS is processing your return, you do not want to have to amend a second time. It is a cumbersome process.
Click
here for instructions on how to file an amended return. During the amendment process, you will be prompted with a list of items you would like to add and you can go to the Health Insurance section and select that her son was covered (you don't actually add any of the information from From 1095B - you just select that you had insurance).
