What's interesting to me about Ford Pines is that he thought his great niece and nephew would be down with sending Dipper to live with him full time.
First of all, they don't know him, they know Stan. Even though Stan lied, he's still the great-uncle the twin's parents are familiar with. Ford is essentially a stranger that looks like Stan.
Second, there's nothing in canon that would make him think this at all. This is a leap, brought on by being raised by Filbrick and then trapped in other dimensions for decades.
Third, Dipper is twelve/thirteen. Most parents would not send their preteen or very young teenager to live with a relative they barely know, let alone one they do know.