Legal Question in Real Estate Law in Maryland

There are no such "official" forms. It's possible that a realtor might have an in-house form that they use, but if you are not working with one, it might be difficult to obtain. If you have a property under contract which gives you the right to assign it to another buyer without the seller's consent, you can simply draw up a statement that says "I hereby assign all of my rights and obligations under the contract between (seller) and (buyer) dated xx for the sale and purchase of real property located at (address) to (assignee). The assignee should then sign stating that they accept the assignment and acknowledge that they are bound by all of the terms and conditions of the contract.