To what extent did they 'agree' to the change of name a year ago? You say you 'agreed' to do it. But did they agree to the new name? Eg did you inform them abou

To what extent did they 'agree' to the change of name a year ago? You say you 'agreed' to do it. But did they agree to the new name? Eg did you inform them about your name or reach any sense of resolution. Unless they could somehow prove you have wilfully be continuing to violate their trademark I don't see how any damages are valid. I would certainly not give in to their threats. What about the origins/timeline of the name and the trademarks. Who was using it first? What exactly is their trademark? Subject to answers above, and given that this is a side project to you - I would suggest you simply write back stating you don't feel you are violating their trademarks, but would consider a rebrand in your mutual interests to avoid any potential for customer confusion provided they contributed to the cost of paying an advertising agency to create a new logo and other menu costs and estimate their share of those costs as $5,100 (eg they pay you what they are asking from you)