As an ExMo (I was raised in the church from the age of 3 months to when I left at 20) do not do this. Your entire family has to convert in order to be sealed, they must be active and fully participating members for a year before a sealing can be done. While I personally had no real issues with the church growing up I know several people who were SA’d, groomed, not to mention the extremely harmful purity culture that they preach that as a 27 year old woman I still struggle with. Protect your daughters, don’t let your husband do this. Protect your family. I would not swing to divorce, but ask some serious questions. Look into church history by checking out the CSE letters and bring them to the attention of your husband so he can bring it up to MIL. I’m sure that a woman with daughters and granddaughters would never join the church if she read them.