The Cabinet which is the center of power is " federalised". This means that many factors such as regions/ provinces, language, religion, ethnicity, gender etc. must be taken into consideration when the Cabinet is chosen.
Each province must be represented; the large provinces like Ontario, Quebec must have more members; language, English and French are key and so is religion... Catholic ( Quebec) and Protestant ( Ontario and others), regions with distinct and very important agriculture and industry must be represented and the growing multicultural population has become a top priority too.
So here we go......1. Each province. If no one is elected from the governing party, then a Senator from that prov. may be selected or someone else from another party ( like when Horner, a Conservative joined the elder Trudeau's cabinet),.or someone, not elected but who must then seek election.
2. Large provinces like Ontario (4-9) and Quebec (4-7) and B C (2-4)
. 3. there must be at least one English speaker from Quebec and at least one French speaker from outside ( maybe New Brunswick, the only official bilingual province)
4.Protestant, Catholic representation, usually Quebec/Catholic and OPntario etc. Protestant.
5. Finance usually go to Toronto; Agriculture to the Prairies or S. Ontario; Justice to Quebec ( Civil law); Fisheries to Maritimes or B C ; Forestry to B C or Quebec; Ethnics ( usually Jewish, Italian, Greek, Sikhs when Liberals are in power and Ukrainian, ( especially) when Conservatives are in power, also the already mentioned).
6. Maybe younger members may be appointed as Junior ministers to allow them to get some experience and also to try to attract young voters
In the just concluded election, the Liberals will form a minority government and they did not elect anyone from the resource and agriculture rich, Saskatchewan or Alberta and must find someone to represent these two provinces in the Cabinet. Perhaps Trudeau ca appoint, long-serving Ralph Goodale ( who lost his seat) to the Senate and name him to represent Sask. and must find someone from Alberta ( probably do as his father did and lure a Conservative
It is a time-consuming and very delicate task and it is perilous to ignore the " cabinet conventions".