If I understand you correctly, you need a line of credti onthe property you are retaining to cover the shortfall on the property you are selling, correct? Loans, whether lines of credit or traditional mortgages cannot be transferred from one property to another. You would have to apply for a new line of credit to be secured against the property you want to keep. I hope I understand the situation correctly. Let me know if I'm off base here.
Best of Luck,
What you may need is a buisiness line of credit that won't show up as a lein against either property. This could act as a sort of bridge loan. I work with a mortgage broker who offers such a product. Let me know if you would like her contact information.
Houlihan Lawrence, JV Office