
when’s the mom going to get in the picture? will daddy change the moment mom comes around?

Not in the near future (based on the current arc in the manhwa). There's going to be a timeskip of 4 years (Leonie will be 12 by then) where the stepmom will appear. She'd probably appear in a few months or maybe next year if they decided to end the season like in the novel (which will have a hiatus/season break). Stepmom appears at the start of in season 2 (novel).
Pelio made it clear that Leonie is his no. 1 priority. He said to Varria (stepmom), that even though he loves them both, if there ever comes a time where they're both in danger, he'll no doubt go save Leonie.
can someone enlighten my why did wolf’s father 2nd wife’s left? is she the one who tried to assasinate the 1st and 3rd wife or smth?
I think that's what was implied, yes.
in the world setting Nobles can have Multiple wives and it never states if she Left or if she was basically just the Second wife due to Politics that kind of thing because even in OUR WORLD there were many times in human history in which Kings and other Nobles had MANY wives or married off their own Daughters to other Noble families in an attempt to make them Allies which Expands a families total Value to the Monarchy