If you can carefully explain how it would help your future plans, how it complements your btech, reason for study pg certificate instead of masters , show it’s relevance back home etc and show stronger ties back home then you’re good to go
Every temporary visa application has a dual intent and you fit right in since you’ve applied for a permanent visa application in the past. Would be difficult explaining you’d return to home country but not impossible. But your chances of visa is 40-60
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It would be best to apply for study permit then subsequently apply for work permit for your husband. It’s easier that way. You need at least 45,000$. Tuition (say 15,000) + 10,000( living expenses for you only ) + (15,000 $ for husband & child) then you need money for your accommodation...
Cause the study plan would explain into details everything and clearly make the VO understand why Canada, how it helps employment, why choosen program, etc