So you "want" a bigger house right now, thus you are considering buying a home and dumping your current house equity defiency on another? Rather than simply staying put for the time being or covering any short amount to sell now, which you admit you can readily do?
Do you know how that sounds? You have no true hardship that REQUIRES you to sell now. You could rent out your current home, or sell it now and THEN buy.
I, for one, will NOT assist two able bodied, employed people not experiencing any true hardship (other than maybe our kids may need to share a room for a while or I'll have to make do without more bathroom) in walking away from their responsibilities. You AGREED to pay back your loan. You did not agree to only pay back your loan IF you didn't "want" more house NOW.
Adoptive parents ARE "real" parents. Sharing genes is not what makes you a "parent"!