Complained family issues

my mom had past in a very shocking way this past November . I have two sibings 11 year old sister and 5 year old brother and they are acting out really bad. And I'm the older half sister but i living a different state as them and i was wondering if and how i can try to reach out to them same way or even help calm things down over there somehow. I never lived with them because my parents got divored when i was 2. And my mom got a bf of 10 plus years and had these two hellions lol. And my dad remarried. Its nothing crazy bad just not listening to any adults and stubborness and talking back stealing and my sister was caught smoking ciggs and brother is getting into trouble in school every other day. And he gets throws violent fits its just alittle overwhelming for the dad. And talking to them is not helping because they just dont listen. Any way if you have any sugguestions please comment