Please Need help ! Immigrant visa f4 interview

[TOMSWAYER10]

Any body can help please ....

I received letter for attending interview for 01st week of November 2017 for me spouse and three childrens aged 16 /12/& 5
My problem is my parents are sick & aged no one to lookafter . Is it possible to extend the date of travel for my spouse and 2 younger childrens? if possibble
how long they can stick here what i can do now ? please help

[inadmissible]

If they are granted an immigrant visa, it will be valid for one year

[TOMSWAYER10]

Many thanks but one doubt

If they are granted an immigrant visa, it will be valid for one year

but one one doubt . if me & my elder son can attend the interview first and if they granted the visa and the rest of them can join with in one year later after
attending the interview ?? I heard a option about following to join but not clear anybody can help me ??