There was some speculation before we got the synopsis for Brotherhooves Social that we'd see more members of the mane six's families including Fluttershy's brother. That didn't end up being the case, so the folks of Twitter got curious and asked Jim Miller if we could expect him sometime this season.
Well, according to Jim he won't be making an appearance this season so we'll have to be on the lookout in season 6 for our shy pegasus' brother!
Thanks to Eagc7 for sending it in!
Fluttershy Brother mention was at a panel at SDCC.
Source
Twitter: Calpain