Am I able to seal my father's 2nd wife to her parents. All her other ordinances have been done. My husband says I can't because she is not my direct line. Then why could the other ordinances be done. I'm confused.
Yes, you can because she is your father's wife. But you should not do any ordinances for her parents because you are not related to them. This is a situation when we have been instructed to complete the sealing to parents even if no ordinances have been done for the parents so that all that person's individual ordinances are completed. It won't be effective until her parents ordinances are completed by the appropriate family, but that is fine. (This is from a presentation by Ron Tanner of FamilySearch sometime last year. Unfortunately, it would take far too long to find it again.)
Sealing a 2nd wife to her parents would fall under the category of "Direct-line ancestors (parents, grandparents, great-grandparents, and so on, and their families)." (emphasis added) Your father is a direct-ancestor and his family is all his wifes and all his children.