I help my smaller dog play with her bigger brother sometimes
That sounds nice of you. Do you do it for safety?
Yes and They enjoy each other, so I let them play together.
That's great to have a pet and a companion for it. You should do what makes it happy.
I think it's sad that she's the alpha dog. I would have made her the puppy and have the big one be the alpha.
I think it is great you let them play together. You should just make sure to be extra careful so she doesn't get hurt. Sometimes dogs can get pretty rough and not realize their own strength.