Okay, when I looked up Dalton and saw that it meant valley (similar to Dean) I really liked it. While I was looking in the D part of the alphabet, I found some others to consider:

Jacob Damian
Jacob Donovan
Jacob Dominic

How do these compare to the short list above?

I like Dalton best but Jacob Dominic is nice too.

If you really wanted to you could put Jacob as his middle name and give him a different first name, so like you call him Jacob but start to introduce his new first name by the time he gets old enough to realize he will never know the difference. You get what Im saying because alot of people call their kids by their middle name but they learn that they have a first name....I went to school with two girls that did that, ones name was Jessica Ann and the others name is Jessica Paige they both go by their middle name. But I think Jacob Nolan is cute.

I love the name Jacob Alexander, and its great since he would have a family middle name, even though there is a Jake in the family. I think having that middle name would really reenforce the idea that he is a part of the family, and he would be included in the tradition.

Jacob Alexander would be my first pick
Jacob Dalton would be my second

I really love the name Jacob so its nice that your not gonna change that name but maybe jacob lee or like you said it may be nice to go with a family name