I'm a newbie. I used to use Travelocity. I opened MilagePlus account for me and after different account for my wife. Never redeemed miles. Now we both have lots of miles, plus I got United credit card (connected to my account) and more miles.
So, the question is: Can I just join our miles or accounts? We fly always together.
I basically want to buy tickets using both miles. Is that possible?
Also, should I keep adding miles to her and my account or keep them all together in my MilagePlus?

Thank you for help.