If we did not marry or live together until December 11, 2010 AND we both have custody of our children from previous relationships can we each file separate tax returns as "Head of Household" for 2010?

“If we did not marry or live together until December 11, 2010 AND we both have custody of our children from previous relationships can we each file separate tax returns as "Head of Household" for 2010?”--->You mean you didn’t live together from Jan 1 2010-December 11, 2010??? Then I guess so as long as you meet the conditions to claim HOH filing status; for example, you can file your return as HOH if you are unmarried( or you are considered unmarried on the last day of the year; this means that you are legally separated from your spouse under a divorce or separate maintenance decree, or married but lived apart from your spouse for at least the last six months of the year), have cared for a dependent, child(ren) whom you can claim as a dependent under the qualifying children rules, for over half the year, and paid more than half the cost of maintaining a home.