Believe me this will help you a lot.

Metalicana<brothers>Igneel
Metalicana + Porlyusica
-Gajeel (17)
-Juvia (16)
-Pantherlily (14)
-Happy (14)
-Carla (14)
(Happy, Pantherlily and Carla are fraternal Twins)

Igneel + Grandine
-Zeref (19)
-Aries (16)
-Natsu (16)
-Wendy (14)
(Natsu and Aries are Fraternal Twins)
Grandine <Twins> Porlyusica

Layla + Jude
-Mavis (19)
-Loke (17)
-Lucy (16)
-Michelle (14)

Jude <Brothers> Rufus

Rufus + Minerva
-Sting (16)
-Rouge (16)
-Frosh (14)
-Lector (14)
(Lector and Frosh are also Fraternal Twins and so are Rouge and Sting)

Aquarius + Scorpio
-Jellal (17)
-Mystogan (17)
-Siegrain (17)
-Levy (16)

Ur + Silver
-Ultear (17)
-Lyon (16)
-Gray (16)
(Lyon is adopted)

Angel + Jackal
-Mirajane (17)
-Elfman (16)
-Lisanna (14)

Makarov (Grandpa)
- Laxus (17)

Gildarts
-Erza (17)
-Cana (16)

Everyone else stays in it's normal Families