fmil Problems🙃

My fiancé and I planned on getting married on June 21 because his grandmother and god mother from Tennessee would be here in New York visiting. It’s very important to us that they are there because they’re amazing people! When we told his family we were getting married those two women were the most supportive and only ones offering help ALL THE WAY FROM TENNESSEE! While my FMIL did not take it well (never said congratulations and stared at the floor), she apologized for her negative reaction. Then I offer to invite her to join my fiancé, my mother and I to visit the venue and the only thing she said in the entire hour was “you cannot do that date, your sister won’t be home you can’t do that”— IN FRONT OF EVERYONE! My fiancé is not close with his sister, she lives in England and only comes home once a year for the past 4 years of living there. It is more important to my fiancé (and myself) that his grandmother and godmother are there than his sister and he told his mother that. Now his mother and father are not returning his calls. WHAT DO WE DO?! So upset for my fiancé and I’m not sure how to handle the situation. Help?