Wraparound mortgage - Wikipedia, the free encyclopedia15 Sep 2008 ... A wrap-around mortgage is a form of secondary financing in which a seller extends to a purchaser a junior mortgage which wraps around and ...
en.wikipedia.org/wiki/Wraparound_mortgage - 18k -

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Note added at 42 mins (2009-03-28 18:36:44 GMT)
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French Business Dictionary: The Business Terms of France and Canada - Google Books Resultby Morry Sofer, Agnes Bousteau, Simon Boisvert - 2005 - Reference - 416 pages
... la toile worm ver worth valeur wraparound mortgage hypothèque intégrante, hypothèque complémentaire, (C) prêt hypothécaire intégrant wraparound type ...
books.google.mu/books?isbn=0884003116...

Without more context, difficult to know. This could be even a third or fourth mortgage/charge.

Based on what you indicate here is a recap of the situation as I see it:
1) There is a private sale of property between Seller and Buyer.
2) Seller agrees to finance the sale transaction.
3) Buyer’s debt obligations (essentially payment of interest and repayment of loan principal to Seller) are to be secured by a registered first (ranking) mortgage in favour of Seller, on the property sold.
4) In addition to the principal contracting parties (Buyer and Seller), a so-called ‘repayment bank’ intervenes in the transaction and agrees to grant additional financing (usually a revolving operating facility) and/or provide various services.
5) Normally, the purpose of such a facility is to finance property-related expenses (repairs, tenant improvements, etc.), pending collection of rentals.
6) As security for the repayment of any sums owing to it from time to time under the facility or for services rendered, the ‘repayment bank’ stipulates that it be granted a charge on the same property.