New PR - what can be filed/claimed now

Hello, family member recently got PR status (start of 2026). Due to them being a senior they will be dependent on us. They also have a disability (hard of hearing - legally deaf).

I am wondering can we file taxes for them now, so they can start getting things like GST credit? I know we can't claim them as a dependent until 2026 taxes next year - and along with that disability credit

Anyone know if they would be eligible for other credits this year? We are in Alberta so we were looking at AISH but I guess that is for people of working age that are looking to be in the work force?

Thanks in advance