Ok , let's do this!
Hello, I'm a senior software architect with many years of experience designing big and complex applications. I have knowledge of the different methodologies and documentation you have to do on each one, like you know, the right methodology depends on how big and how fast is the project changing.
Let me help you with this, not only creating the three diagrams but if you want I can give you tips and recommendations.
Let's talk soon, I really look forward to be part of your team.