The position for the Martells was added in the later books of ASOIAF meaning the War of the Five Kings. The position does not exist during the current alloted period. However, the Targaryens are very, very, very closely affiliated with the Martells so it is possible they have residence and/or influence within the city.There is actually a position in the Small Council of a representative for Dorne. So maybe one of them has that?
He can be married if you want him to be; you can leave him single however. If you wanted, you could say his wife has passed away! He could always meet someone during the rp...Hmmm...should Bryant have a wife? He is almost thirty, so it wouldn't be unheard of for him to be unmarried, but then again he's also Lord of his House, so he was probably married off young.