I have read your project description, i understand what you want, and i would like to offer you my services. I can scan the altered theme and find all the changes and transfer them to new child whenever possible, and document all other changes. I have years of experience with all required technologies (Wordpress, WP themes development, PHP&MySQL, HTML&CSS, JS, jQuery), so i can finish this project quickly, without errors and to your full satisfaction. In case you would like to discuss the project with me or get started, feel free to contact me by private message. I'm looking forward to our cooperation.