Hi RSP,
You will find that most of the pipes are contained within the walls, floor/ceiling space of the unit below or may be in a service duct, but you will need to locate these as a starting point to work out what needs to be done.
You will need to arrange a plan to be prepared showing what is currently in place and another showing what you intend to do. I would also suggest it would be prudent seeking an exclusive use by-law to be prepared, granting you the rights to do the works and defining responsibility to maintain, extending to the total joining of the apartment.
Mr S