D and E, two brothers, are partners in a Pizza restaurant. They have a 3-year lease on their restaurant from F. After one year, D wants to leave this business and open up an up-scale Italian restaurant on his own, but only if he can obtain a release from the current lease. D and E told F of D's plans, and F said, "That's fine, if E continues his obligations under the lease, D can be released." D and E both said, "Ok." They signed a written document with F confirming this modification of their agreement. In reliance on this, D opened up a new restaurant, mortgaging all of his property to fund the restaurant's initial start-up costs. E has now filed for bankruptcy and F wants to proceed against D for the remaining 2 years on the lease arguing that the modification is not enforceable. What likely result, and why?