do they have any legal definition?
No, there is no comprehensive legal definition of Métis status in Canada.
Métis
. There is no comprehensive legal definition of Métis status in Canada; this is in contrast to the "Indian Act", which creates an Indian Register for all (Status) First Nations people. 
who set up indian residential schools in canada Christian churches. is the government involved? Yes, it was funded by the Department of Indian Affairs of the Canadian government. did any deaths take place there? Yes, it is estimated to range from 3,200 to upwards of 6,000. what are its effects? Historic trauma resulting in loss of culture along with prevalence of sexual abuse, alcoholism, drug addiction, lateral violence, mental illness and suicide among Indigenous peoples. did anyone have to apologize? Archbishop Michael Peers on behalf of the Anglican Church of Canada . what was vatican's response? It released an official expression of sorrow on the church's role in residential schools. was the archbishop a part of any ministry? Yes, the ministry on the prairies. in what capacity? He was considered to be a keen sympathiser with the ideals of prairie populism. what was the purpose of the schools? To remove the Indigenous children from the influence of their own culture and assimilating them into the dominant Canadian culture, "to kill the Indian in the child." which groups of these people live in the country? The First Nations, Inuit and Métis. where are the third group of people based? In  Canada and parts of the United States between the Great Lakes region and the Rocky Mountains.
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Métis [SEP] Lack of a legal definition
It is not clear who has the moral and legal authority to define the word "Métis". There is no comprehensive legal definition of Métis status in Canada; this is in contrast to the "Indian Act", which creates an Indian Register for all (Status) First Nations people. Some commentators have argued that one of the rights of an Indigenous people is to define its own identity, precluding the need for a government-sanctioned definition. The question is open as to who should receive Aboriginal rights flowing from Métis identity. No federal legislation defines the Métis. Alberta is the only province to have defined the term in law under the "Métis Settlements Act" (MSA), which defines a Métis as "a person of Aboriginal ancestry who identifies with Métis history and culture".