Where are Quicksilver’s sisters?

In Days of Future Past, Quicksilver has two sisters – one of whom is presented in the movie. Although he is introduced in X-Men: Apocalypse with his mother, there is no sign of anybody else living with them. And since his character arc revolves around the idea of a family, this seems a bit weird to be – to not have his sisters appear.
Of course, this would mean other underdeveloped characters, considering that one of them is the powerful Scarlet Witch. However, since these characters are not pulled straight out of the comics, this could have been basic fan service, like in Days of Future Past, with all those future characters.
And it would have been great, since it would have given a continuity to Quicksilver’s arc – he has a family, but he also searches for his long lost father. Did Fox try to avoid any confusion between the mutant Scarlet Witch and the miracle from the MCU?
It would be a shame if this isn’t addressed in future movies. Especially since Scarlet Witch would be a great opportunity for Fox to reboot the entire X-Men franchise (yeah, I am ok with that, if it happens at the end of another trilogy).
