As my mobility part of PIP was not allowed I asked for them to reassess there decision and also send me all information that they used. Yesterday I received there report a 28 page document and it has a short but very important paragraph on page 25. This is an exact quote.
(Although they have not claimed under the terminal illness provisions, in my opinion they are terminally ill under the prescribed definition
So if RA is a terminal illness then they cannot take away any section that you had from your DLA. I have spoken to them and I am waiting for a call from a manager to put this to them. Because under the terminally ill section it says that you do not need to fill in the form for PIP all you need to do is get your Dr to right a letter on the DS1500 form. I will keep you all informed of what happens.