Standard Visitor visa

[Hemmaa]

Hi Guys
Now, I have a Tier 5 Visa (Government Authorized exchange) my visa will ex pier on 28/04/2016.
I have invited my mother and sister before as a family visitor visa last May.
Now, I want to invite my family again to visit me (Mother, Sister and Brother) for 2 weeks only.
But the Problem i am affraid from my visa becuse it will expaire after nearly 2 months and this may be a reason for the border to refuse their visas.
Or let them apply for general visa and do not send to an invitation and they applu as a general visitor or tourist.
2nd Q.
The documents that they will use to submit must be up to date if these documents are on date from last October, It is ok or now

Many thanks