There's no such thing as a renewal;, you need to male a new application.
Parents should provide proof of their personal funds, not yours.
Invitation letter is not a requirement for TRV.
You are in a tough and understandable situation but the one who has full custody has all the cards unfortunately and decides what's best for the children. You need to start with a custody issue.
1. Send a Use of a Representative Form (IMM 5476) via webform.
2. The lawyer's access will be revoked.
3. You can link it in the express entry account.