Northern California car accident

My brother was driving my car. GEICO policy holder rear ended my car. My car was totaled and my brother was injured. They have paid me for the car. They now need to pay for my brother’s injuries. He lost 6 weeks of work from the shoulder injury. He went to the er and then his primary and orthopedic doctor and still needs to go to physical therapy. Both his knee and his shoulder were strained. He had x rays and they show arthritis existing. He can’t afford to miss more time off work The adjuster said for my brother to send proof of his time lost. She said to leave an amount of what we want to receive on the message. How do I know what to ask for? Is there a common amount? He is financially hurting. He probably should have knee and shoulder surgery but he can’t because he needs to work. I assume he wouldn’t get that covered very well because of the existing arthritis. He is old and still has to work. He is a carpenter and still can’t lift his arm up all the way. What things do we count beyond the lost wages. Obviously I can’t ask them what we can count as damage? We don’t have an attorney and can’t afford one so we have to do our best. How do I know what things I should be including beyond the wages. We are out about 20k for 6 weeks. Can we ask to just start with wages while we work on the rest? That is a lot of money to us that we lost and we need some money to catch up asap. The accident was June 2025. We’re not looking to get rich but considering he will probably need the two surgeries down the road but after losing so much, we just can’t afford to get them done now. Thank you