Welcome to the forums. Opening up a card under his account will not help because I assume he has a different Rapid Rewards number. What you could do is open up a different SW cc under your RR number and the points will combine...good luck!
You're saying I can open up two different SW cc's on my name (using the same RR number)? That simple?
Tell me if I have my calculations right: 40k + 40k = 80k sign up and then I'd need to spend another another 11k within 12 months (actually before the end of December so that it posts in 2019) on one card = 20k bonus, plus another 11k within 12 months on the other card = 20k bonus, Total: 120k points = companion pass.
Then I book myself a flight with all those points and DH comes along for free??? Where were we till now???