Would it be possible to to a trigger (for message or email) to a guest on a specific day of the week as long as they are staying at the rental (and also maybe a 'grace period'). For example, I like to send a message every Thursday to whomever renters are occupying the rental at the moment to request that they take garbage out to the road for a Friday Morning pickup. Hence if they stay there over the course of three Thursdays, that reminder would go out every Thursday. An optional grace period such as 1 or 2 days would eliminate the message being sent if they for example arrived on a Thursday.... I guess either a grace period OR just the elimination of day of arrival from the trigger.