How long does the pain relief effect of steroid injection last? And how many times can inject?
Steroid injection has osteolytic effect which can cause further damage to the joint. She only 32 years old, still got long way to go.

Based on her description, possible is Patellar femoral mal-tracking/instability problem. A trained physiotherapist might be able to help with this. It might take time to train the correct muscles, so patience is needed.

So depends on TS, is she looking to treat the pain? or to fix the problem?

If treat the pain, then go for pain killers, steroid injections. But remember these are temporary pain relief.

If want to fix the problem, go to a physiotherapy and follow the proper exercise protocol. Train the correct muscle that holds on to the patellar (since patellar is a sesamoid bone that is floating and fully dependant on the muscle for stability).

How to start? step by step

1. manage the inflammation first
a) can take antioxidant
b) take NSAID....

...when pain reduced, then

2. physiotherapy

....when muscle is stronger, then

3. then supplements to improve joint cartilage (does not matter what brand, as long as is original and buy from pharmacy)

4. continue to self exercise, have healthy lifestyle (you are solely responsible for your own health, not the doctors or physios or anyone)