My question involves real estate located in the State of: Quebec Canada

I don't know if any of you have experience with Canada or even Quebec, but here goes:

House in Quebec co owned by father and son. House is primary residence of son and his family, son paid mortgage for almost 3 years. Father suddenly without notice decided to take over mortgage payments. Son went on vacation and father has entered house without notifying son and allowed brother in law also to enter house while inhabiting family were away. Father knew the family was away and did not yet know a return date.

Son had set up a neighbor to watch house and was notified that someone had entered house with a key. Son asked father about it, father and mother said they do not feel they need to let son know when they want to enter house; they pay mortgage and so are responsible.

Questions: Can co owner come and go as they please in home when they are not the inhabitants of the house? Can they have others enter house? Do they need to notify co owner that they or another person will enter when the inhabitant is away? (There is nothing written about any of this dictating access but father, mother and son are all on deed - son 50%, father 25%, mother 25%.)

Son has it in writing that father has now said since he pays the mortgage he is responsible. would this stand up in court for damages if through accident, negligence etc. son and family suffered any loss of their possessions while away since father has now stated he is responsible and knows they are away and will be entering the house at will without notification?

Thank you.