If you are not immediate family (e.g. son/daughter, brother/sister) I wouldn’t push this issue - unless the deceased left specific instructions it is usual for the next of kin to make decisions pertaining to the deceased’s body. When a family is grieving for a husband/father they are unlikely to take kindly to the perception of someone telling them what to do with the remains because it’s the requirements of the Church. (I’m not saying you are forcing this issue but these issues are so very delicate and people aren’t always thinking straight when grieving.) Presumably they will have a Catholic funeral so it may be better to ask the parish priest to approach this subject.
This is one of those reasons why people should make clear instructions before death, it’s clears up any confusion and takes a burden off the family.