Why was Booth admitted into the presidential box?

[Anita]

Thanks Roger and Toia for the information on witnesses that saw Booth hand Forbes a card. I've been reading and re-reading material related to this topic and now believe that whether or not Forbes took a drink with Booth that night, he was back after intermission. Evidently Mary Lincoln didn't believe Forbes guilty of any involvement because she gave him Lincoln's frock coat and other personal items belonging to Lincoln.

I'm still a bit confused about the card. I thought the purpose of a calling card was to give it to a messenger who would take the card into the President to announce the person who wished to see him, while the caller waited outside.

Since Forbes knew who Booth was why not give Forbes his own card? If Booth used his own card perhaps Forbes, wishing to distance himself from having let Booth pass, threw it away not wanting the assassin's card on him. Since Booth was in love with Lucy Hale would he have wanted to involve her by using her father's card?