Flowbot can transfer to Chatbot (and vice versa)... (OR do not require Flowbot to always have a button/action!)

Sometimes we just want the user to talk to us - for example, I have 2 chatbots that talk about very different things.  I don't want a user to accidentally get a response about a different subject.  For example a user who wants to buy or sell a car might go something likke this:    FLOWBOT:   Do you want to buy a car or sell a car?  [BUY] [SELL].  <transfer to chatbot>. CHATBOT:  Ok, what would you like to know?  ...  This allows the user to narrow down to a subject but still have the freedom to ask a large number of questions.   

The reverse is also helpful, for example the chatbot might say at some point.  CHATBOT: If you are ready to buy your insurance, type YES.  If the user types "yes" then it transfers to the Flowbot:  FLOWBOT: What is your name?  <USER INPUT>. Do you want comprehensive cover [YES] [NO] etc etc...  and at the end transfer back to chatbot.. "Do you have any other questions"?