How come Arnold and Willis's family members never took time to come see them every week or months?

I thought it was established in the episode ‘the relative’, that they didn’t have any (the plot in general is far fetched). even their cousin myrtle waters, who ends up trying to scam me Drummond, was a surprise to them.

Willis and Arnold were both created in a petri dish ;)

I've always wondered at that oversight as well, Confidence30. You would've thought that both of Arnold and Willis' deceased parents, Henry and Lucy Mae Jackson, had other relatives--siblings, nephews, nieces, and assorted cousins--scattered across the country; surely one of Arnold and Willis' otherwise unmentioned relatives would've ultimately paid a visit to Drummond's penthouse on Park Avenue in the heart of Manhattan to see how the boys were doing.

The lack of visiting relatives for Arnold and Willis is often cited as one of the show's biggest logic gaps. While the series focused on the boys' transition to Park Avenue, the "missing" family members from Harlem were largely ignored by the writers for several reasons:

The "Total Orphan" Narrative
The premise of Diff'rent Strokes relied on the boys being completely reliant on Mr. Drummond. If they had a supportive network of aunts, uncles, or grandparents in Harlem, the legal and emotional justification for Mr. Drummond—a wealthy white businessman—taking them in would have been much harder for 1970s audiences to accept. By portraying them as having "nobody else," the show simplified the adoption arc.

Specific Family Mentions
When the show did address relatives, it usually felt "far-fetched" or served a specific plot point:

The Relative (Season 1): You’re thinking of Cousin Myrtle Waters (played by LaWanda Page). She was introduced as a distant relative from Detroit. Her visit didn't lead to a lasting connection; instead, she overstayed her welcome by faking an injury to stay in the penthouse.

The "Scam" Relative (Season 2): In another episode, a man appeared claiming to be a relative to contest the adoption. It was later revealed he was only after a potential inheritance, reinforcing the idea that any "long-lost" family they had might not have the boys' best interests at heart.

Why They Didn't Visit
Narrative Clean Break: The writers wanted to emphasize the "fish out of water" aspect of the boys living in a wealthy world. Regular visits from Harlem family would have grounded them too much in their old life, potentially undercutting the "rags to riches" fantasy the show sold to viewers.

Friends vs. Family: Instead of relatives, the show occasionally brought in their old friends from Harlem (like the "Tarantulas" gang or their friend Dudley) to remind the boys of their roots without complicating their legal status as Drummond's children.

It’s definitely a plot hole that two kids from a tight-knit community like 1970s Harlem wouldn't have at least one aunt or neighbor who checked in regularly, but the writers chose to prioritize the "Drummond family unit" above all else

the "white savior" premise is as curdled milk.