1)    An ill person, or a woman who has given birth or other similar person, may eat meat during this period. Nevertheless, if it is not difficult for them, they should refrain from eating meat at least from the seventh of Av, as on this day the non-Jews entered the holy temple. (Mishne Berurah 551)

2)    At a meal celebrating the fulfilment of a commandment, such as circumcision, redemption of the firstborn etc., one may eat meat and drink wine. This leniency applies only to a person who attended this meal because of closeness or friendship. One who comes just in order to be able to eat, has sinned. ((Shulchan Aruch and Mishne Berurah 551). Some have a custom not to eat meat even at such a meal. (Ben Ish Chai Devarim 16)