Is traveling to Canada and residing there for three years to obtain its citizenship, then returning to the Gulf or Jordan, unlawful according to Sharia, and will one be held accountable for a sin that one of their grandchildren might commit in the future as a result of that?

It is not permissible to obtain the nationality of a disbelieving country without an urgent necessity, just as it is not permissible to travel to reside in lands of disbelief except for those who possess sufficient knowledge and piety to repel desires and doubts, and who can observe the rituals of their religion. Travel and residence in lands of disbelief are fraught with dangers to one's religion and children. The responsibility lies with the parents in raising their children. If residence is religiously permissible and the father is keen on raising his children in obedience, then he will not be held accountable for their actions after they reach puberty and maturity. However, if residence is forbidden and leads to the loss of the children, then it is feared that the father will bear the consequences of that on the Day of Judgment.