Drowning in College Loans

My daughter-in-law accrued a huge debt with college loan. Needless to say, they are drowning under the debt. They have two little children and each work full-time, but neither of their jobs pays big. Meghann joined the army reserves to help with her debt, but it is not enough. Was just wondering what steps they should take in conquering these huge debts (close to $100,000)? We have helped them financially in so many ways, but can’t keep helping as we have other children and more importantly want them to work through this. Would so appreciate your advisement.