Mental and Physical harassment by In-Laws and husband

Hello Sir/Madam, Its been a year since my sister got married and has an 8months old baby boy. Everything was ok during engagement but at the time of marriage, the guys family that includes his sisters and mother started demanding for dowry such as jewels, motorbike. We did make arrangements for jewels but with regards to the motorbike, the one that they specifically wanted was due and we promised to get them at the earliest. After the wedding evening, they demanded bracelets for their son and until till then they dint allow the bride to get inside their house. Though we were financially drained we still managed to make arrangements and bought them bracelet and rings and only after which she was let inside the house. She was already carrying at the time of marriage and she went through all mental tortures at her inlaws house. Many times she came to her parent's house to eat as she was not provided with food there. All expenses so far was made by her parents that include medical,food for baby as her husband is currently jobless and when she asks her husband to look for a job as she cant always be dependent on her parents, her mother-in-law and sister-in-law keeps yelling and torturing her. They used to take her jewels without her knowledge and gave it to the elder sister-in-law and when my sister about the jewels they keep abusing, taunting, demoralizing and putting her down in front of her parents. Several times she was sent back to her parent's house and as usual, they used to advise her and push her back to that Gravesend. This is been happening since the day she got married. They used to take her jewels and say that its their sons property now and that they can use them. Recently her sister-in-law was having the baby and when my sister asked for the baby to feed him, she denied giving the baby to her and said that its her brother's child and that she doesn't have any rights to touch the baby and was abusing her with profanity language. Not able to withstand this she slapped her and took her child and her sister-in-law slapped her back and her mother-in-law started yelling her and her husband came from behind and started hitting her aggressively and she was locked out of the house. She was always denied her rights in the house, she was denied from her rights with her child, persisted denial of food, she had no privacy inside her bedroom, was threatening divorce and was under continuous mental and physical torture. I'm unable to withstand this shift and I wanted to file a complaint. As I am currently in Canada, I'm not sure where and how to proceed with it. Kindly advice.