Praise be to Allah.
It is not essential for those who are invited to the ‘aqeeqah meal to know that it is an ‘aqeeqah. If someone invites others to a meal and does not tell him that the meat is an ‘aqeeqah that he slaughtered, that is permissible and the ‘aqeeqah is valid, because it is not stipulated in order for the ‘aqeeqah to be valid that the one who eats from it should know that it is ‘aqeeqah. But it is better to inform him of that so that he may pray for the newborn to be guided and blessed.
And Allah knows best.