"Αυτή και ο πατέρας μου είναι αδέλφια."

Μετάφραση: She and my father are siblings.

[christos1042]

brothers?????

[glavkos]

Αδέλφια ανεξαρτήτως αν είναι αγόρια ή κορίτσια = siblings

http://www.oxfordlearnersdictionaries.com/definition/english/sibling

[jeanprendiville]

Christos, siblings is correct but it would be more usual to say " are brother and sister".