Disability Claim And Court Ordered Child Support

I have custodial custody of my 13 year old son and have for the past 5 years. His mother is now going to receive disability. She has started a modification with Domestic Relations to have the support order terminated? Can this be done? She is claiming more money will be given from the disability claim so I should agree to sign off the order. I don't feel the increase in the amount is the issue here. I live in Pennsylvania, is this true? I don't want to terminate a court order that protects my son to get what is due to him. I can't afford a lawyer at this point in time. Thank you in advance for any help you may be able to offer.