I decided to find out where this bit of trivia came from and give it a read - it's from the Official Fanbook (i.e the second one).

The full text is as follows: https://twitter.com/Naracooga/status/1360602627277479942

"The surprising scrapped background of Calamity Mary and Lapis Lazuline

Calamity Mary and Lapis Lazuline were actually planned to be mother and daughter. Although the plot point was dropped, you can still see it in their designs; under Mary's left eye and Lazuline's right,

they both have a mole, and the eyes themselves also look quite similar. Lazuline's zebra print cloak and tail were intended to match Mary's leopard print bikini."

Even though the link was never actually mentioned in the story, both of their family situations line up well enough,

and there's nothing that explicitly goes against this as headcanon, I believe. There's an implication that Lazuline wasn't a magical girl until after Mary was, which is interesting from Fav's perspective cause it means he'd much rather pass up on a good magical girl (Lazuline)

if it meant he could get an interesting one (Mary).

I've recently been putting together a timeline of events, which is a little tricky since MGRP as a whole isn't very precise with dates and stuff, but there's enough room for Lazuline to become a magical girl between when

Mary does and the events of Restart. The timing's quite tight, taking various side stories into account, but it's just about possible