You can “help” your parents with a pro se filing — but you cannot “do it for them”. Only individuals who are licensed attorneys are permitted to prepare and file pleadings and other documents with a court on behalf of others.
While individuals can certainly represent themselves in any court case “pro se”, a person who is not licensed as an attorney cannot represent someone else, nor file paperwork on their behalf — even if they are family members.
So while you can help them with the process, it is critical that your parents fully understand what legal steps they are taking, that they alone are making those decisions themselves.