Help to send our family to Michigan so my husbands family can see his military promotion

My amazing husband is in the USAF and will be promoted on March 1st. We are stationed in Oklahoma and want his family to be able to be present for the ceremony's since this will most likely be his final promotion in the AF before he retires from service. We have decided to do the ceremony in Michigan so all of his family including his Grandmother whom all live in Michigan can attend. I am a stay at home mom to 4 amazing kiddos and my husband obviously is the one who provides for us. I want to be able to take some of the stress of costs from the trip off his mind. He is always thinking about our future and making sure he can provide the best for myself and our kiddos. I would love to be able to let him know that our trip consisting of 6 airline tickets and rental car are taken care of. Thank you for your support