Am I sinful for not enjoining good and forbidding evil within my family , for example like not advising my sister/mother to cover their awrah because I know their reaction and that they won't listen, and I privately make dua that Allah guides them. Am i someone who lacks gheerah?

Ustadh AbdulAziz al-Haqqan

No no, you have to exercise wisdom as well, meaning you put the advice in its proper place and u find ways that would make them listen, but if you advised and u see that it doesn't affect anything and it causes more harm then there is nothing on u.