How do you say Happy Birthday Sister in Hungarian?

Answer 1

in Hungarian we don't distinguish the words brother and sister...

both are mean one: testvér [tɛʃtveːr]

but, if you want to say the gender of your brother or sister, you can use:

boy (brother) is: fiútestvér [fiuːtɛʃtveːr]

girl (sister) is: [laːɲtɛʃtveːr]

Answer 2

The Hungarian for sister is lanytestver.