The first time that Hub had had a child, he wasn't married.
It had purely been for science, to see if another Navi's data was compatible with Hub's. Of course, Hub being who he was, his father and brother had asked him for permission to perform something like that. They didn't want to make Hub a father against his will, after all, even if Lan was over the moon about being an uncle.
But Hub had seen Patch, his brother's baby. He'd played with him whenever he was in Copybot form, and he loved his nephew immensely. Even Lan had noticed that Hub would pick up Patch whenever the two of them were around, and Patch loved his "Uncle Mega".
"I want a child," Hub had said wistfully one day.
"Well, like Dad and I said, the offer is on the table," Lan told him with a shrug. "I'm sure that you and Roll have been wanting a child for awhile, once the two of you finally tie the knot."
While Hub and Roll had been wanting to get married for ages, they had agreed to wait until Mayl finished her doctorate