We manipulate people all the time, our parents (and children) included. Guilt-tripping, appealing to God, to their sense of self-worth, you name it. They have done it to you, you have done it to them. The difference is that most of the time it is done subconsciously. It might be that doing it intentionally is too repugnant for you for whatever reasons. It is also possible that the actual amount of manipulation you may have to do is lower than you think, or that you might have to work over someone you care about less.

For example, in a hypothetical case that you would convince their pastor/rabbi/mullah into believing that God wants all his children to use all available technological and medical advances to extend their life (not such a far-fetched idea), and that cryonics is one of those advances, and he would preach it to the congregation one day, then you can rely on his word when explaining that you, personally, want to use it for yourself. From there it is not that large a leap to include the rest of your family into the picture.