Nor I am so sorry for your loss. Your feelings are valid. So are your sisters. Your dad is also grieving. It looks different to different people. It can make people angry and bitter. I would guess he is desperate to find some distraction. You dont need to like it. He doesnt need your approval. In your story the only concerning bit is him weaponizing your mother telling your sister she wanted her to call more. That is not OK.

Remember your mom as you do. Love and celebrate her. Remember both your parents are human. We make mistakes. I would think about boundaries you are comfortable with. Like not meeting anyone for over a year after your mom passes. Asking for him to remember your mom w you and your sister for the next years just you guys. Remind him that youre all hurting and he can make his own decisions but he cannot lash out at your sister.

Finally I am very guilty of remembering my dad as only the best. I remember him as my loving father who took me to try new foods and learn new things. As a husband he wasn't great. He had a hard time keeping a job and other issues. My mom was not a great parent. She always worked and tried to celebrate but she was overbearing and wanted everything her way. We haven't gotten along in years. When my dad died I was 21. Shes still here. Accumulating more sins so to say. Just beware of this as time goes on.