欢迎来到我们的家人 is wrong if you mean "welcome to our family". It would be a different meaning if you have a comma: 欢迎来到, 我们的家人 Welcome my family members. To answer your question: 到 means you had reached the place. 来到 = had arrived.

欢迎来到我的家

对，应该是“欢迎来到我们家”

As a native Chinese speaker, I think this sentence is wrong. I guess it should be 欢迎来到我们的家. which means welcome to our house.