“This user is not a member of this group. Add them to the group and promote them to admin?” is currently translated as “Esse usuário não é um membro do grupo. Adicioná-lo ao grupo e promover à administrador?”. This is grammatically wrong. “This” was translated as “esse”, which is closer to “that” than it is to “this”. The proper form to translate “this” is “este”. “À”, in Brazilian Portuguese, can only be used before words in their feminine form; “administrador” is in the masculine form (“administradora” is the feminine equivalent), so the preposition should be “a” instead. The verb “promote”, as the verb “add”, should be translated followed by the equivalent pronoun that refers to admin (just as the verb add “adicionar” became “adicioná-lo”, promote “promover” should be translated as “promovê-lo”). Therefore, the correct translation for these two sentences is “Este usuário não é um membro do grupo. Adicioná-lo ao grupo e promovê-lo a administrador?”.