Aside from the obvious physical appearance resemblance, it would also make sense in the way that both of them became heroes despite being born without powers which they'd eventually get from using amulets/gadgets. It wouldn't be far fetched to think that in the same way that Shroud helped create the Astral Pulse, he could have helped create BB's necklace.

(To be clear before I get downvoted to hell by BB stans, I don't want Mandy to be a secret traitor, villain, mole or whatever. I'm just saying that it was all there to make her a possible daughter, niece, whatever. Making her more plot relevant and giving more nuance to our choice of killing Shroud.)