Sonic Underground's New Sis

The Sonic Underground siblings are a tight-knit trio of triplets who save Mobius, but what happens when they get a new sister named Sarah? Or when it turns out that future boy Silver is there older-younger brother? NOTE: This is my first actual fanfic, so it may not be all that great. CONSTRUCTIVE criticism is great and appreciated, BUT NOT GOD DAMNED FLAMES? Ya' hear? Great!