Some folks have said elsewhere (https://moviechat.org/tt0086827/Whos-the-Boss/5fea5d99a9e2c1725b6cbb7c/Leah-Remini-as-Tonys-daughter) that Leah would've in hindsight, been more believable as Tony Danza's daughter than Alyssa Milano. Maybe because, they have a more similar on-screen attitude and way of talking.

What's ironic is that Alyssa Milano like Tony Danza and Leah Remini (https://www.youtube.com/watch?v=8E2NmBaeGZc), really is from Brooklyn. And if you look at the early seasons (in particular, the first season) of Who's the Boss?, Alyssa as Sam, does speak with a pretty heavy and pronounced New York accent.

I guess that when the more tomboyish aspects of Sam's personality were gradually toned down and she presumably became more assimilated to the suburban life in Connecticut, the Brooklyn-ness became watered down. In real life, when Alyssa started acting, she worked with a dialect coach to lose the Brooklyn accent. But when she first got cast in Who's the Boss?, she had to put it back on.

Charlie according this video (https://www.youtube.com/watch?v=XFYb1sRZb8w) was written to be kind of the darker half of Samantha. In other words, Charlie would probably be Sam if she never left Brooklyn and never met and moved in with people like Angela, Mona, and Jonathan.