I want our family to be treated better by my sisters

My sister lives very far from us and we meet rarely. We each have young kids similar ages. We arranged to meet for lunch this weekend, to exchange gifts. We will only spend half a day with them & it’s a 4-5 hour drive with our kids and dogs. On the exact same afternoon we planned to meet, another sister has now arranged to take my nieces and nephews out to the theatre so we will barely see them. My kids were not invited. Doing thought work I see that I’m really angry with both my sisters mainly because my kids have not been included and will likely be hurt and disappointed. Also I feel a victim – that I’m making so much effort & Love is not reciprocated. I feel very angry and ready to voice my frustration or cancel going. I know this is not a good place to act from. From the manual I understand other people can act however they want. But I want my family to treat us with respect. Is this a situation where I could reasonably set a boundary, or at least tell my truth? How can I regain my power here?