Hello Phil
Before I try to answer your query, your full name is showing on your post; if you would like to change this go to
My full name is showing, how can I stop it? There is no reason why you shouldn't send a copy of your DLA appeal letter when claiming your PIP, but be aware that there is no guarantee that it will be taken into consideration. Doubtless you will be sending other supportive evidence, just include it in with this.
Good luck with your application