How are you legally related to the "4 dependents from a previous relationship" that you take care of? Did they live with you all year?

They are my children and yes they have been living with me all year.

In the interview you will choose the marital status as married and then choose to NOT file a joint return and when you enter in any qualifying dependents the Head of Household filing status will be suggested.

How did you file for 2016 and 2017?

In the interview you will choose the marital status as married and then choose to NOT file a joint return and when you enter in any qualifying dependents the Head of Household filing status will be suggested.