The allonge is to be completed if/when the loan is "sold" or otherwise transferred to a different holder of the note .
The allonge is to be retained by the lender and completed if/when the loan is "sold" or otherwise transferred to a different holder of the note ("lender"); at which point the executed allonge is given to the new lender. The allonge is the document that transfers the promissory note in a similar way the Assignment of Mortgage transfers all beneficial interest under the mortgage.
The allonge is included with "Yes" to the Mortgage Assignment data field on the Property page.