Trying to help a family member with their student loans, don’t know where to start.

Basically, I have a family member that has had issue with with their student loans. Their parents are co-signed. They have been paying ~ $3500/mo somehow but are no longer able to do so. I am asked to help but IDK what to do. My loans have been Federal so I don't have much experience here. Here is what I know:

Sallie Mae:

• $9,800 @ 8.38% fixed
• $27,000 @ 13% variable
• $6,500 @ 11.25% variable
• $6,300 @ 11.88% variable
• $300 @ 8.63% variable

LendKey:

• $14,000 @ 8.12% variable
• $17,300 @ 8.12% variable
• $23,000 @ 5.77% variable
• $20,000 @ 5.77% variable

My instinct is to refinance, especially the Sallie Mae ones because of the high rates. The problem is, this person's parents don't want to co-sign their loan. They want out. The person on their own has about $40k take home per year (without much expenses). Their credit score is ~760.

Any advice would be helpful but I also have some specific questions:

• Can I refi only a few of these loans and not all of them?
• Would only refinancing the high interest ones be easier based on their income and credit score or does it not make a difference?
• Where to refi? I heard Sofi, Laurel Road, Earnest, Common Bond, and local credit union. Anywhere else?
• Any other option aside from refinancing? Maybe something I am not thinking of.

Thank you in advance.