We would to by a newly constructed home in our community before someone else does. Problem is we have a home with and existing mortgage that we would need to sell before we could buy the new house. That may take months and the possibility of the new house selling first is very real. Current mortgage balance is approximately $168,000 with a property value of approximately $200,000. We would like to offer the builder our current house plus money for the new house. Is this legal and if so how would you go about it?