Sister in law help!!

I’m having a small immediate family wedding next year. (About 50 people). Me and my FH were only having a best man (his brother) and 2 maids of honor ( my sisters). We don’t have many close friends and felt this was best. However, his brother is getting married this year and I will have a future sister in law. She knows the type of wedding we are having and I was planning on including her in everything. Over the weekend she made a comment about my bachelorette trip and that she will help if I pick her. I didn’t know what to say and the conversation went elsewhere. If my FH was having more people I would absolutely have her as a bridesmaid but after all it just a title. What should I do ??