Usually you can't make your heirs take the vows (unless it's by event) and enatic means, that only women inherit. So either you'll be unable to make your last daughter take the vows (or any of them, because of gavelkind) or you'll end up with a game over, because you have no eligible heirs.
1. Enatic/Agnatic Clans will force pure enatic/agnatic succession at the time of reformation, but you are allowed to later switch to enatic-cognaic/agnatic-cognatic succession.
2. You can force your heir to take the vows if you have them in prison.
You do get 40 tyranny for imprisoning without a reason, but excommunication is considered a valid reason. If you reform with hierocratic or autocephalous leadership you can then spend 100 Piety to get your heir excommunicated, imprison her, and force vows.