The Form 8962 Instructions, Premium Tax Credit (PTC), page 10, state:

Allocating policy amounts. You need to allocate policy amounts (enrollment premiums, SLCSP premiums, and/or APTC) on a Form 1095-A between your tax family and another tax family if:

1. The policy covered at least one individual in your tax family and at least one individual in another tax family, and
2. Either:
   1. You received a Form 1095-A for the policy that does not accurately represent the members of your tax family who were enrolled in the policy (meaning that it either lists someone who is not in your tax family or does not list a member of your tax family who was enrolled in the policy), or
   2. The other tax family received a Form 1095-A for the policy that includes a member of your tax family.

For example, if you could have claimed your child as a dependent, but chose not to, follow the instructions below to report their health insurance on your return.

1. Click Federal. On smaller devices, click the menu icon in the upper left-hand corner, then select Federal
2. Click Health Insurance in the Federal Quick Q&A Topics menu to expand that section and then click Coverage information
3. Select the form you received and proceed through the interview questions
4. On the screen titled Health Insurance - Nondependent Coverage select +Add Health Insurance to enter your child's coverage information

If you could not claim the child as a dependent, the child should enter the information on his or her own return (you must provide a copy of the Form 1095-A you received in this case).