An immovable whose dwellings are all occupied by undivided owners, can be converted into divided co-ownerships, subject to certain conditions. But carrying out this conversion requires to overcome several steps involving all owners concerned.
The purchase of a condo leased to a third party is a frequent occurrence in the resale market. Save for an agreement to the contrary, nothing prohibits a co-owner lessor from selling and a purchaser of purchasing an apartment even though the tenant wishes to continue to reside in it.
The lease is attached to the immovable, not to the co-owner/ lessor. The lease will continue to be in force even if the unit is sold and the terms and conditions of the lease shall remain the same.