OK, all understood. The bottom line seems to be that if the expenses contributing to the HOH are actually 50-50 - and in case, they claim to pay ALL house expenses from a common checking account to which they both contribute 50% - then it seems from a practical standpoint that the two of them will simply have to come to an agreement as to which will file as HOH with their respective dependents and which will have to file as Single. I don't really see any other choice
