For the purposes of their registration, mortgages on the lots of an immovable subject to the status of co-ownership are deemed not to encumber the share of the common parts included in these lots. However, registered creditors exercise their rights over the said share as it exists at the time of the transfer, the price of which forms the subject of the distribution; this share is considered to be encumbered by the same securities as the private portions and by these securities only.