Dona Inês de Castro is referred as a sobrinha of King Pedro of Portugal, because she was the daughter of one of the king's blood cousins. She had the same great-grandfather as Pedro of Portugal, which was King Afonso III of Porugal. For that reason, a dispensation from the Pope was required for Inês and Pedro to be married. [Pedro, ch. 28: 77-79]
An 'alcaide-mor' had jurisdiction over a province or a fortified city. In English, the word 'governor' often implies civil (i.e. juridical) and military governance, which is also the case with the Portuguese office of 'alcaide-mor'. Compare with Alcaide. (CW)
Counsellor. [See: Armando Luis de Carvalho Homem, Conselho real ou conselheiros do rei? A propósito dos 'privados' de D. João I, offprint of Revista da Faculdade de Letras do Porto (Porto,1987), 26-30.]