So for context, my fiance's only brother is in the military. It is currently November while I am writing this. We found out the night that we got engaged that he will be deployed overseas from May/June, until about Christmas time. We wanted to have a fall wedding around September/October and do not want to wait until fall 2024 due to my grandmothers declining health. She has early onset dementia and some days are better than others. My whole family and I would be devastated if she could not attend the wedding/remember the wedding if we wait until 2024. My fiances opinion is that his brother knew by joining the military that he would be missing events and that is the commitment he made when he signed up. However, my future mother-in-law has very strong opinions. Her whole life is her 2 boys. She is very opinionated and not afraid of conflict. Of course we would like my fiancés brother to attend, but we are not pushing the wedding to 2024 due to my grandmother. Another point is that even if we push it to 2024, brother will still be in the military and still no guarantee that he will be able to attend. Are we in the wrong for wanting my grandmother there over his brother?