Am not an expert but based on my own service connection can offer the following:
- As mentioned, the regional VSO (Veteran Services Officer?) will be a great resource. There are usually multiples VSOs in a region that work thru various veteran orgs (VFW, Legion, etc). The VA may also be able to refer you and your father to one locally.
- To change a previously issued rating, a new claim should be expected that substantiates the increased rating. Depending upon the disability, some disabilities will naturally worsen with age... this is taken into consideration as the VA evaluates the claim (some worsened disabilities due to age are not ignored, and can result in a higher rating being provided).
- I'm not aware of a way to fast-track claims/reviews... to the VA's credit, their processing has improved in recent years. My experience was a judgement issued on a claim to be sub-60 days. Key to a timely claim and review is a thorough package of evidence... missing docs & evidence introduce delays.
Good luck and thank you for helping your father. Thank you for his service.
Cheers!