I suppose I would remember this:
You don't need a solicitor to write to his, you can do that yourself, save your £ for if it goes to court.
You then have a paper trail stating that your DD is hostile to contact "When DD said on x that "she was done with you" she meant it. I have spoken to her a few times to and she is clear that she does not wish to see you.
Paper trail of the WHY your DD does not want to see him
Paper trail of asking him to attend family therapy (do your research regarding how much protection DD will get from a therapist - ie it should be individual therapy)
Paper trail of YOUR concerns - re his drug use, his inappropriate conduct to DD1
Paper trail of YOUR suggestion as to how to restart contact - starting off slowly to build up as DD is ready
Don't rush to reply, he has said 14 days so just ensure your response is with his solicitor before that (day 12 to be sure?). This will draw out negotiations hopefully and delay it going to court. All the time your DD is getting older, not being forced to have contact, there is a bigger lapse since she had contact.
What I have said you should suggest above would be "usual" for re-establishing contact - him proving to be drug free, at a neutral place (guess she is too old for a contact centre but you could stipulate that too
), and to build up contact slowly...
This is all a paper trail that you are merely supporting your DD and in principle are happy to work with her to reinstate contact.
In the meantime hope he gets bored especially if his solicitor explains that he may well have to do some of what you have suggested... will he really bother to jump through hoops to see DD?