Australia tourist/visit visa how to obtain visa grant letter copy

[dar8]

Hi , My sister and her family are permanent residents here and we are on a 489 visa , she applied for a visit/tourist visa for our parents , they said it was granted for a 12 months continuous stay and then have to go back home and then spend 6 months away from Australia before they can apply for another visa to come here. The thing is we have an infant and since im studying and since we are not supported for childcare we want to apply by ourselves and bring our parents next year because my brother in law who is the one who applied for my parents visa is kind of a selfish bum head and always lie about things and wants to give us a hard time , when they apply visa for parents they want both of them to stay with them only , so my parents asked them for a copy of their visa to see the conditions of it , the expiry date and etc. and they are refusing to give them a copy , i asked for it and they keep refusing to send me a copy , I told them that i will be applying for my parents visa next time in order to help us with our lil one and they said not to do that and that they will apply for it and will send one of them over here for a few months when needed , the thing is my parents wants us to apply for the visa from next tym because my sister and selfish brother in law kind of act like they own them and my parents have to do whatever they say just because they applied for their visa ( stupid i know they have this we are pr we are citizens we are superior than you mentality ) ,  my parents have travelled here multiple times and kind of think that the visa is granted for 3 years multiple even though my sister says it's only for 18 months with 12 months continous stay. There is no way for me to verify correct details of their visa because my brother in law does not want to send us a copy of it. The last thing i want to do is to apply for a visa for them when one already exist. My parents proided me with scanned copy of their passport but you need the grant number or receipt number to check details on vevo which i or my parents do not know   , i tried to use the revive grant number function on website it still asks for the email address details which was used to apply for the visa which is my brother in laws and i do not know that info. Is there a way to find out info about my parents visa , and obtain a copy of their visa grant letter without going through my brother in law? i dont have the details to request the reference number online , i do not know what visa subclass , grant dates or expiry dates , or conditions of it. Apprweciate if someone can help

[snifter]

I'd probably be seeking professional advice. I'd hope there is a way for your parents to get their visa info but if your brother is not complying they may need to go via official channels.