Don't need to incorporate her at all. She is basically an unknown character to the wider audience. No following in the comics. Marvel has no idea if people will even be receptive to her as a concept. They're Forcing it right now honestly.
Way different compared to say X-23 who had some popularity in comics before being in movie as wolverines clone/daughter.
And even then she was introduced in his third solo movie and after he appeared in like 8 films overall.
Blade hasn't been in shyt yet, they need give him some time to shine before giving it to another character with the same abilities.
It's not the same though. For 1, Brielle only been around for like 8 months, and only been on the table for maybe a decade (Fallon Grey was the original idea). Her creation was solely to incorporate her into a potential Blade movie. By your only theory, you don't know how people will respond to Blade as a character either, so doing both doubles the chances that either will be popular. I said like 8 years ago that it seemed that Marvel would probably only do team-up flicks going forward, and here were are. If it's not Brielle, it's going to be another character in the team-up.
Wolverine's solo movie was already in motion when X-23 debuted in X-Men Evolution, so his trajectory was already planned. And Wolverine is like one of the handful that could do a solo. Blade isn't on Wolverine's level. Hell, most of the fans of the Blade movie had no clue it was a comicbook or Marvel character until the 3rd one. And they aren't fans of the comicbook character and have no idea how the new interpretation of the character will be. You can't want Wesley's version, but someone else in the role. Goyer wrote the treatment, but Wesley incorporated his entire style and demeanor into the character that gave it that extra oomph. It wasn't all Wesley, since the personality had already been displayed in the Spider-Man cartoon, but a collaborative effort. If Ali did his own take based on his personality, he's be more like the 70s/80s blaxploitation, laid back Blade.
I actually liked Sticky's interpretation on Spike TVs highest rated premier ever, and I watched that entire series from episode 1 to cancellation. He wasn't the problem.
They should've never announced a Blade movie to begin with. I stand by that.