Perhaps when you were a child, you fought with your eldest or younger sister. But if the parents just calm down their children and quench conflicts, the result can be a strong friendship of two close and dear people in a more adult age. There is nothing more terrible than when two native people are at enmity especially on a birthday.
When you are both far from jerky teenagers but adult, formed personalities, such a trifle as pictures for your sister's birthday will be important to you. Say your best wishes and give happy emotions to your sister. You will want to send your beloved native or cousin funny e-cards congratulation, or beautiful images with flowery inscriptions.